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110 results on '"Wooldridge, E"'

1. "You can't handle the truth"!

Author

Wooldridge, E. Tyler, CAPT

Subjects
NAVY - United States, DISSENTERS, LEADERSHIP, LOYALTY, CRITIQUES
Abstract

illus bibliog

Published
2000

2. A tale of two cities

Author

Wooldridge, E. Tyler, III, CAPT

Subjects
NAVY - United States, MILITARY SERVICE AS A PROFESSION, OFFICERS - Navy - United States, TOURS OF DUTY
Abstract

illus

Published
1999

3. Five and out?

Author

Wooldridge, E. Tyler, III, CAPT

Subjects
OFFICERS - Navy - United States, RETENTION OF MILITARY PERSONNEL
Abstract

illus

Published
1998

4. Design and operations of load-tolerant external conjugate-T matching system for the A2 ICRH antennas at JET

Author

Monakhov, I, Graham, M, Blackman, T, Dowson, S, Durodie, F, Jacquet, P, Lehmann, J, Mayoral, M-L, Nightingale, M P S, Noble, C, Sheikh, H, Vrancken, M, Walden, A, Whitehurst, A, Wooldridge, E, and contributors, JET-EFDA

Subjects
Physics - Plasma Physics
Abstract

A load-tolerant External Conjugate-T (ECT) impedance matching system for two A2 Ion Cyclotron Resonance Heating (ICRH) antennas has been successfully put into operation at JET. The system allows continuous injection of the RF power into plasma in the presence of strong antenna loading perturbations caused by Edge Localized Modes (ELMs). Reliable ECT performance has been demonstrated under a variety of antenna loading conditions including H-mode plasmas with Radial Outer Gaps (ROG) in the range of 4-14 cm. The high resilience to ELMs predicted during the circuit simulations has been fully confirmed experimentally. Dedicated arc detection techniques and real-time matching algorithms have been developed as a part of the ECT project. The new Advanced Wave Amplitude Comparison System (AWACS) has proven highly efficient in detection of arcs both between and during ELMs. The ECT system has allowed the delivery of up to 4 MW of RF power without trips into plasmas with Type-I ELMs. Together with the 3dB system and the ITER-Like Antenna (ILA), the ECT has brought the total RF power coupled to ELMy plasma to over 8 MW, considerably enhancing JET research capabilities. This paper provides an overview of the key design features of the ECT system and summarizes the main experimental results achieved so far., Comment: 30 pages, 23 figures

Published
2013
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8. Mining of the association rules between driver electrodermal activity and speed variation in different road intersections

Author

Distefano, N, Leonardi, S, Pulvirenti, G, Romano, R, Boer, E, and Wooldridge, E

Subjects
Urban Studies, General Engineering, Transportation, Safety Research
Abstract

It is commonly acknowledged that the human factor and the interaction between the human factor and the road environment are among the most common causes of road accidents. Physiological signals can provide a real-time assessment of the driver's state because they can be collected continuously without interfering with the driver's task performance or the drivers' perception of the road. This study presents a method for measuring and quantifying drivers' physiological responses when approaching T-junctions and roundabouts using electrodermal activity and speed variations. Speed and electrodermal activity were collected continuously during a driving study which took place on a test environment based at Cranfield University and surrounding roads. Twenty participants were involved in the study. The analysis focused on four crossing manoeuvres on two T-junctions and a roundabout. The association Rule with the Apriori algorithm was used in order to evaluate associations between the variables related to electrodermal activity, i.e. the number and amplitude of the SCR peaks (assessed by the Electrodermal Impact Index in aggregate form), and the variables related to speed, i.e. the speed variation and its sign (positive or negative), for each type of intersection. The main results of this study can be summarized as follows: 1) the rules obtained for the manoeuvres on the T-Junctions show that the T-junctions induce low variations in the electrodermal activity and are often associated with a significant speed increase (between 20% and 30%); 2) the rules obtained for the manoeuvres on the roundabout highlights that the roundabout induces high variations in the electrodermal activity and is associated with a significant speed reduction (between 20% and 40%).

Published
2022

9. Photothermal floats for evaporation enhancement and waterfowl deterrence

Author

Monasmith R., Allred S., Capoccia S., Centurion D.P., Cyr M., Geer J., Moe R., Myhre G., Swenson H., Vasquez B.C., Wooldridge E., Young C., Zodrow K.R., Monasmith R., Allred S., Capoccia S., Centurion D.P., Cyr M., Geer J., Moe R., Myhre G., Swenson H., Vasquez B.C., Wooldridge E., Young C., and Zodrow K.R.

Abstract

Waste storage ponds can present a hazard to migrating birds and some methods of deterrence reduce evaporation, making them ineffective where evaporation is desirable. Inexpensive materials (granular activated carbon, fibreglass, and carbon air filters) have been coated on high-density polyethylene (HDPE) containers to create photothermal floats, which absorb solar irradiation and promote, rather than deter, evaporation. Carbon foam, a buoyant material, was used alone. The materials were tested for their effects on evaporation rates in a laboratory environment at low light intensities (150 W∙m-2). Granular activated carbon displayed the largest improvement in evaporative performance, increasing the evaporation rate by 64% (plus/minus 7%) compared with a control with standing water, and 199% (plus/minus 7%) compared with uncoated HDPE. Materials were characterised using scanning electron microscopy, specific surface area analysis, water retention analysis, contact angle goniometry, and reflectance. Significant differences were found between materials for all parameters and their connections to measured evaporation rates. It is concluded that these novel and inexpensive material combinations may be suitable for maintaining or improving evaporation rates while deterring waterfowl., Waste storage ponds can present a hazard to migrating birds and some methods of deterrence reduce evaporation, making them ineffective where evaporation is desirable. Inexpensive materials (granular activated carbon, fibreglass, and carbon air filters) have been coated on high-density polyethylene (HDPE) containers to create photothermal floats, which absorb solar irradiation and promote, rather than deter, evaporation. Carbon foam, a buoyant material, was used alone. The materials were tested for their effects on evaporation rates in a laboratory environment at low light intensities (150 W∙m-2). Granular activated carbon displayed the largest improvement in evaporative performance, increasing the evaporation rate by 64% (plus/minus 7%) compared with a control with standing water, and 199% (plus/minus 7%) compared with uncoated HDPE. Materials were characterised using scanning electron microscopy, specific surface area analysis, water retention analysis, contact angle goniometry, and reflectance. Significant differences were found between materials for all parameters and their connections to measured evaporation rates. It is concluded that these novel and inexpensive material combinations may be suitable for maintaining or improving evaporation rates while deterring waterfowl.

Published
2020

11. Mode Conversion Heating in JET Plasmas with Multiple Mode Conversion Layers

Author

Van Eester, D, Lerche, E, Johnson, T, Hellsten, T, Ongena, J, Mayoral, ML, Frigione, D, Sozzi, C, Calabro, G, Lennholm, M, Beaumont, P, Blackman, T, Brennan, D, Brett, A, Cecconello, M, Coffey, I, Coyne, A, Crombe, K, Czarnecka, A, Felton, R, Gatu Johnson, M, Giroud, C, Hellesen, C, Jacquet, P, Kazakov, P, Kiptily, V, Knipe, S, Krasilnikov, A, Lin, Y, Maslov, M, Monakhov, I, Noble, C, Pangioni, L, Proverbio, I, Stamp, M, Studholme, W, Tardocchi, M, Versloot, TW, Vdovin, V, Whitehurst, A, Wooldridge, E, Zoita, V, JET EFDA contributors, GORINI, GIUSEPPE, NOCENTE, MASSIMO, Van Eester, D, Lerche, E, Johnson, T, Hellsten, T, Ongena, J, Mayoral, M, Frigione, D, Sozzi, C, Calabro, G, Lennholm, M, Beaumont, P, Blackman, T, Brennan, D, Brett, A, Cecconello, M, Coffey, I, Coyne, A, Crombe, K, Czarnecka, A, Felton, R, Gatu Johnson, M, Giroud, C, Gorini, G, Hellesen, C, Jacquet, P, Kazakov, P, Kiptily, V, Knipe, S, Krasilnikov, A, Lin, Y, Maslov, M, Monakhov, I, Noble, C, Nocente, M, Pangioni, L, Proverbio, I, Stamp, M, Studholme, W, Tardocchi, M, Versloot, T, Vdovin, V, Whitehurst, A, Wooldridge, E, Zoita, V, and JET EFDA, C

Subjects
FIS/01 - FISICA SPERIMENTALE, JET, plasmas
Published
2010

12. Experimental investigation of ICRF heating scenarios for ITER’s half-field Hydrogen phase performed in JET

Author

Lerche, E, Van Eester, D, Johnson, T, Hellsten, T, Ongena, J, Mayoral, M, Frigione, D, Sozzi, C, Calabro, G, Lennholm, M, Beaumont, P, Blackman, T, Brennan, D, Brett, A, Cecconello, M, Coffey, I, Coyne, A, Crombe, K, Czarnecka, A, Felton, R, Gatu, R, Giroud, C, Hellesen, C, Jacquet, P, Kiptily, V, Knipe, S, Krasilnikov, A, Maslov, M, Monakhov, I, Noble, C, Pangioni, L, Proverbio, I, Stamp, M, Studholme, W, Versloot, T, Vdovin, V, Whitehurst, A, Wooldridge, E, Zoita, V., GORINI, GIUSEPPE, NOCENTE, MASSIMO, TARDOCCHI, MARCO, Lerche, E, Van Eester, D, Johnson, T, Hellsten, T, Ongena, J, Mayoral, M, Frigione, D, Sozzi, C, Calabro, G, Lennholm, M, Beaumont, P, Blackman, T, Brennan, D, Brett, A, Cecconello, M, Coffey, I, Coyne, A, Crombe, K, Czarnecka, A, Felton, R, Gatu, R, Giroud, C, Gorini, G, Hellesen, C, Jacquet, P, Kiptily, V, Knipe, S, Krasilnikov, A, Maslov, M, Monakhov, I, Noble, C, Nocente, M, Pangioni, L, Proverbio, I, Stamp, M, Studholme, W, Tardocchi, M, Versloot, T, Vdovin, V, Whitehurst, A, Wooldridge, E, and Zoita, V

Subjects
ICRF, hydrogen, ITER
Published
2010

14. Experimental investigation of ion cyclotron range of frequencies heating scenarios for ITER's half-field hydrogen phase performed in JET

Author

Lerche, E., Van Eester, D., Johnson, T.J., Hellsten, T., Ongena, J., Mayoral, M.L., Frigione, D., Sozzi, C., Calabro, G., Lennholm, M., Beaumont, P., Blackman, T., Brennan, D., Brett, A., Cecconello, M., Coffey, I., Coyne, A., Crombe, K., Czarnecka, A., Felton, R., Giroud, C., Gorini, G., Hellesen, C., Jacquet, P., Kiptily, V., Knipe, S., Krasilnikov, A., Maslov, M., Monakhov, I., Noble, C., Nocente, M., Pangioni, L., Proverbio, I., Sergienko, G., Stamp, M., Studholme, W., Tardocchi, M., Vdovin, V., Versloot, T., Voitsekhovitch, I., Whitehurst, A., Wooldridge, E., Zoita, V., and Contributors, JET-EFDA

Abstract

Two ion cyclotron range of frequencies (ICRF) heating schemes proposed for the half-field operation phase of ITER in hydrogen plasmas—fundamental H majority and second harmonic 3 He ICRF heating—were recently investigated in JET. Although the same magnetic field and RF frequencies ( f ≈ 42 MHz and f ≈ 52 MHz, respectively) were used, the density and particularly the plasma temperature were lower than those expected in the initial phase of ITER. Unlike for the well-performing H minority heating scheme to be used in 4 He plasmas, modest heating efficiencies ( η = P absorbed / P launched

Published
2012

15. Latest Achievements of the JET ICRF System in View of ITER

Author

Durodié F., Monakhov I., Nightingale M., Mayoral M.L., Argouarch A., Berger-By G., Blackman T., Cocilovo V., Czarnecka A., Dowson S., Frigione D., Goulding R., Graham M., Hobirk J., Huygen S., Jachmich S., Jacquet P., Lerche E., Loarer T., Maggiora R., Messiaen A., Milanesio D., Nave M.F.F., Ongena J., Rimini F., Sheikh H., Sozzi C., Tsalas M., Van Easter D., Vrancken M., Whitehurst A., Wooldridge E., Zastrow K.D., and JET-EFDA Contributors

Subjects
____
Abstract

____

Published
2010

16. Potential of the ICRF Heating Schemes foreseen for ITER’s Half-Field Hydrogen Phase

Author

Lerche E., Van Eester D., Johnson T., Hellsten T., Ongena J., Mayoral M.L., Frigione D., Sozzi C., Calabrò G., Lennholm M., Beaumont P., Blackman T., Brennan D., Brett A., Cecconello M., Coffey I., Coyne A., Crombe K., Czarnecka A., Felton R., Giroud C., Gorini G., Hellesen C., Jacquet P., Kiptily V., Knipe S., Krasilnikov A., Maslov M., Monakhov I., Noble C., Nocente M., Pangioni L., Proverbio I., Stamp M., Studholme W., Tardocchi M., Versloot T., Vdovin V., Whitehurst A., Wooldridge E., and Zoita V. ane JET-EFDA Contributors

Subjects
____
Abstract

____

Published
2010

17. Latest Achievements of the JET ICRF Systems in View of ITER

Author

Durodié, F., Monakhov, I., Nightingale, M., Mayoral, M. L., Argouarch, A., Berger By, G., Blackman, T., Cocilovo, V., Czarnecka, A., Dowson, S., Frigione, D., Goulding, R., Graham, M., Hobirk, J., Huygen, S., Jachmich, S., Jacquet, P., Lerche, E., Loarer, T., Maggiora, Riccardo, Messiaen, A., Milanesio, Daniele, Nave, M. F. F., Ongena, J., Rimini, F., Sheikh, H., Sozzi, C., Tsalas, M., Van Eester, D., Vrancken, M., Whitehurst, A., Wooldridge, E., and Zastrow, K. D.

Published
2010

18. ICRF heating: the JET experience and prospect for ITER

Author

Mayoral M.-L., Ongena J., Argouarch A., Blackman T., Bobkov V., Calabrò G., Durodié F., Frigione D., Gauthier M., Goulding R., Graham M., Huygen S., Jacquet P., Lerche E., Monakhov I., Nave M.F.F., Nunes I., Nightingale M., Rimini F., Sozzi C., Van Eester D., Vrancken M., WhiteHurst A., Wooldridge E., and JET-EFDA contributors

Subjects
____
Abstract

___

Published
2009

19. Realisation of a prototype superconducting CW cavity and cryomodule for energy recovery

Author

Mcintosh, P. A., Bate, R., Beard, C. D., Cordwell, M., Dykes, D. M., Pattalwar, S., Strachan, J., Wooldridge, E., Belomestnykh, S., Liepe, M., Padamsee, H., Buechner, A., Gabriel, F., Michel, P., Kimura, T., Smith, T. I., Byrd, J., Corlett, J. N., Li, D., and Lidia, S.

Subjects
Elbe, accelerator, cryomodule, energy recovery, accelerator RF
Abstract

For Energy Recovery applications, the requirement for high-Q accelerating structures, operating in CW mode, at large beam currents, with precise phase & amplitude stability and modest accelerating gradients are all fundamental in achieving intense photon fluxes from the synchronised FEL insertion devices. Both Daresbury Laboratory and Cornell University are developing designs for advanced Energy Recovery Linac (ERL) facilities which require accelerating Linacs which meet such demanding criteria. The specification for the main ERL accelerator for both facilities dictates a modest accelerating gradient of 20 MV/m, at a Qo of better than 10^10, with a Qext of up to 10^8. A collaborative R&D program has been set-up to design and fabricate a ‘proofof-principle’ cryomodule (which is well underway) that can be tested on ERLP at Daresbury and also on the Cornell ERL injector. This paper details the new cryomodule design, provides an insight to the design solutions employed and reports on the present status of the project.

Published
2007

20. Comparison of different buncher cavity designs for the 4GLS ERLP

Author

Wooldridge, E., Beard, C. D., Gerth, C., and Büchner, A.

Subjects
ELBE, Buncher, RF, Injector
Abstract

A DC photocathode gun is part of the injector of the Energy Recovery Linac Prototype (ERLP) presently being built at Daresbury Laboratory. A buncher is required for the ERLP downstream of the photocathode gun to decrease the relatively long bunches (20-30ps) from the GaAs cathode. Three different single-cell cavity designs were investigated: the Cornell buncher, the ELBE buncher and an EU cavity without Higher Order Mode (HOM) dampers. The properties of these cavities were studied with the computer codes CSTs Microwave Studio and ASTRA. The fundamental frequency and field pattern of each buncher was investigated in Microwave Studio. The EU cavity was scaled from 500MHz to the required frequency for the buncher of 1.3GHz. As the anticipated kinetic energy of the electron beam after the gun is about 350keV a particle tracking code including the space charge forces is mandatory to study the effect of the different buncher cavity designs on the beam dynamics. The particle tracking code ASTRA was used to study the performance of the bunchers for a variety of beam parameters. From these investigations it was found that the three bunchers produce very similar effects on the particle bunch.

Published
2004

22. Calibrations and Verifications Performed in View of the ILA Reinstatement at JET.

Author

Dumortier, P., Durodié, F., Helou, W., Monakhov, I., Noble, C., Wooldridge, E., Blackman, T., and Graham, M.

Subjects
ELECTRONIC circuit design, S-matrix theory, ELECTRIC capacity, ELECTRIC potential
Abstract

The calibrations and verifications that are performed in preparation of the ITER-Like antenna (ILA) reinstatement at JET are reviewed. A brief reminder of the ILA system layout is given. The different calibration methods and results are then discussed. They encompass the calibrations of the directional couplers present in the system, the determination of the relation between the capacitor position readings and the capacitance value, the voltage probes calibration inside the antenna housing, the RF cables characterization and the acquisition electronics circuit calibration. Earlier experience with the ILA has shown that accurate calibrations are essential for the control of the full ILA closepacked antenna array, its protection through the S-Matrix Arc Detection and the new second stage matching algorithm to be implemented. Finally the voltage stand-off of the capacitors is checked and the phase range achievable with the system is verified. The system layout is modified as to allow dipole operation over the whole operating frequency range when operating with the 3dB combiner-splitters. [ABSTRACT FROM AUTHOR]

Published
2015
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23. Minority and mode conversion heating in (He-3)-H JET plasmas

Author

Van Eester, D., Lerche, E., Johnson, T. J., Hellsten, T., Ongena, J., Mayoral, M-L, Frigione, D., Sozzi, C., Calabro, G., Lennholm, M., Beaumont, P., Blackman, T., Brennan, D., Brett, A., Cecconello, Marco, Coffey, I., Coyne, A., Crombe, K., Czarnecka, A., Felton, R., Gatu Johnson, Maria, Giroud, C., Gorini, G., Hellesen, Carl, Jacquet, P., Kazakov, Ye, Kiptily, V., Knipe, S., Krasilnikov, A., Lin, Y., Maslov, M., Monakhov, I., Noble, C., Nocente, M., Pangioni, L., Proverbio, I., Stamp, M., Studholme, W., Tardocchi, M., Versloot, T. W., Vdovin, V., Whitehurst, A., Wooldridge, E., Zoita, V., Van Eester, D., Lerche, E., Johnson, T. J., Hellsten, T., Ongena, J., Mayoral, M-L, Frigione, D., Sozzi, C., Calabro, G., Lennholm, M., Beaumont, P., Blackman, T., Brennan, D., Brett, A., Cecconello, Marco, Coffey, I., Coyne, A., Crombe, K., Czarnecka, A., Felton, R., Gatu Johnson, Maria, Giroud, C., Gorini, G., Hellesen, Carl, Jacquet, P., Kazakov, Ye, Kiptily, V., Knipe, S., Krasilnikov, A., Lin, Y., Maslov, M., Monakhov, I., Noble, C., Nocente, M., Pangioni, L., Proverbio, I., Stamp, M., Studholme, W., Tardocchi, M., Versloot, T. W., Vdovin, V., Whitehurst, A., Wooldridge, E., and Zoita, V.

Abstract

Radio frequency (RF) heating experiments have recently been conducted in JET (He-3)-H plasmas. This type of plasmas will be used in ITER's non-activated operation phase. Whereas a companion paper in this same PPCF issue will discuss the RF heating scenario's at half the nominal magnetic field, this paper documents the heating performance in (He-3)-H plasmas at full field, with fundamental cyclotron heating of He-3 as the only possible ion heating scheme in view of the foreseen ITER antenna frequency bandwidth. Dominant electron heating with global heating efficiencies between 30% and 70% depending on the He-3 concentration were observed and mode conversion (MC) heating proved to be as efficient as He-3 minority heating. The unwanted presence of both He-4 and D in the discharges gave rise to 2 MC layers rather than a single one. This together with the fact that the location of the high-field side fast wave (FW) cutoff is a sensitive function of the parallel wave number and that one of the locations of the wave confluences critically depends on the He-3 concentration made the interpretation of the results, although more complex, very interesting: three regimes could be distinguished as a function of X[He-3]: (i) a regime at low concentration (X[He-3] < 1.8%) at which ion cyclotron resonance frequency (ICRF) heating is efficient, (ii) a regime at intermediate concentrations (1.8 < X[He-3] < 5%) in which the RF performance is degrading and ultimately becoming very poor, and finally (iii) a good heating regime at He-3 concentrations beyond 6%. In this latter regime, the heating efficiency did not critically depend on the actual concentration while at lower concentrations (X[He-3] < 4%) a bigger excursion in heating efficiency is observed and the estimates differ somewhat from shot to shot, also depending on whether local or global signals are chosen for the analysis. The different dynamics at the various concentrations can be traced back to the presence of 2

Published
2012
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24. Optimizing ion-cyclotron resonance frequency heating for ITER : dedicated JET experiments (vol 53, 124019, 2011)

Author

Lerche, E., Van Eester, D., Ongena, J., Mayoral, M-L, Laxaback, M., Rimini, F., Argouarch, A., Beaumont, P., Blackman, T., Bobkov, V., Brennan, D., Brett, A., Calabro, G., Cecconello, Marco, Coffey, I., Colas, L., Coyne, A., Crombe, K., Czarnecka, A., Dumont, R., Durodie, F., Felton, R., Frigione, D., Gatu Johnson, Maria, Giroud, C., Gorini, G., Graham, M., Hellesen, Carl, Hellsten, T., Huygen, S., Jacquet, P., Johnson, T., Kiptily, V., Knipe, S., Krasilnikov, A., Lamalle, P., Lennholm, M., Loarte, A., Maggiora, R., Maslov, M., Messiaen, A., Milanesio, D., Monakhov, I., Nightingale, M., Noble, C., Nocente, M., Pangioni, L., Proverbio, I., Sozzi, C., Stamp, M., Studholme, W., Tardocchi, M., Versloot, T. W., Vdovin, V., Vrancken, M., Whitehurst, A., Wooldridge, E., Zoita, V., Lerche, E., Van Eester, D., Ongena, J., Mayoral, M-L, Laxaback, M., Rimini, F., Argouarch, A., Beaumont, P., Blackman, T., Bobkov, V., Brennan, D., Brett, A., Calabro, G., Cecconello, Marco, Coffey, I., Colas, L., Coyne, A., Crombe, K., Czarnecka, A., Dumont, R., Durodie, F., Felton, R., Frigione, D., Gatu Johnson, Maria, Giroud, C., Gorini, G., Graham, M., Hellesen, Carl, Hellsten, T., Huygen, S., Jacquet, P., Johnson, T., Kiptily, V., Knipe, S., Krasilnikov, A., Lamalle, P., Lennholm, M., Loarte, A., Maggiora, R., Maslov, M., Messiaen, A., Milanesio, D., Monakhov, I., Nightingale, M., Noble, C., Nocente, M., Pangioni, L., Proverbio, I., Sozzi, C., Stamp, M., Studholme, W., Tardocchi, M., Versloot, T. W., Vdovin, V., Vrancken, M., Whitehurst, A., Wooldridge, E., and Zoita, V.

Published
2012
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25. Minority and mode conversion heating in (3He)–H JET plasmas

Author

Van Eester, D, Lerche, E, Johnson, T, Hellsten, T, Ongena, J, Mayoral, M, Frigione, D, Sozzi, C, Calabro, G, Lennholm, M, Beaumont, P, Blackman, T, Brennan, D, Brett, A, Cecconello, M, Coffey, I, Coyne, A, Crombe, K, Czarnecka, A, Felton, R, Gatu Johnson, M, Giroud, C, Gorini, G, Hellesen, C, Jacquet, P, Kazakov, Y, Kiptily, V, Knipe, S, Krasilnikov, A, Lin, Y, Maslov, M, Monakhov, I, Noble, C, Nocente, M, Pangioni, L, Proverbio, I, Stamp, M, Studholme, W, Tardocchi, M, Versloot, T, Vdovin, V, Whitehurst, A, Wooldridge, E, Zoita, V, GORINI, GIUSEPPE, NOCENTE, MASSIMO, Zoita, V., Van Eester, D, Lerche, E, Johnson, T, Hellsten, T, Ongena, J, Mayoral, M, Frigione, D, Sozzi, C, Calabro, G, Lennholm, M, Beaumont, P, Blackman, T, Brennan, D, Brett, A, Cecconello, M, Coffey, I, Coyne, A, Crombe, K, Czarnecka, A, Felton, R, Gatu Johnson, M, Giroud, C, Gorini, G, Hellesen, C, Jacquet, P, Kazakov, Y, Kiptily, V, Knipe, S, Krasilnikov, A, Lin, Y, Maslov, M, Monakhov, I, Noble, C, Nocente, M, Pangioni, L, Proverbio, I, Stamp, M, Studholme, W, Tardocchi, M, Versloot, T, Vdovin, V, Whitehurst, A, Wooldridge, E, Zoita, V, GORINI, GIUSEPPE, NOCENTE, MASSIMO, and Zoita, V.

Abstract

Radio frequency (RF) heating experiments have recently been conducted in JET (He-3)-H plasmas. This type of plasmas will be used in ITER's non-activated operation phase. Whereas a companion paper in this same PPCF issue will discuss the RF heating scenario's at half the nominal magnetic field, this paper documents the heating performance in (He-3)-H plasmas at full field, with fundamental cyclotron heating of He-3 as the only possible ion heating scheme in view of the foreseen ITER antenna frequency bandwidth. Dominant electron heating with global heating efficiencies between 30% and 70% depending on the He-3 concentration were observed and mode conversion (MC) heating proved to be as efficient as He-3 minority heating. The unwanted presence of both He-4 and D in the discharges gave rise to 2 MC layers rather than a single one. This together with the fact that the location of the high-field side fast wave (FW) cutoff is a sensitive function of the parallel wave number and that one of the locations of the wave confluences critically depends on the He-3 concentration made the interpretation of the results, although more complex, very interesting: three regimes could be distinguished as a function of X[He-3]: (i) a regime at low concentration (X[He-3] < 1.8%) at which ion cyclotron resonance frequency (ICRF) heating is efficient, (ii) a regime at intermediate concentrations (1.8 < X[He-3] < 5%) in which the RF performance is degrading and ultimately becoming very poor, and finally (iii) a good heating regime at He-3 concentrations beyond 6%. In this latter regime, the heating efficiency did not critically depend on the actual concentration while at lower concentrations (X[He-3] < 4%) a bigger excursion in heating efficiency is observed and the estimates differ somewhat from shot to shot, also depending on whether local or global signals are chosen for the analysis. The different dynamics at the various concentrations can be traced back to the presence of 2

Published
2012

26. Optimizing ion-cyclotron resonance frequency heating for ITER : dedicated JET experiments

Author

Lerche, E., Van Eester, D., Ongena, J., Mayoral, M-L, Laxaback, M., Rimini, F., Argouarch, A., Beaumont, P., Blackman, T., Bobkov, V., Brennan, D., Brett, A., Calabro, G., Cecconello, Marco, Coffey, I., Colas, L., Coyne, A., Crombe, K., Czarnecka, A., Dumont, R., Durodie, F., Felton, R., Frigione, D., Gatu Johnson, Maria, Giroud, C., Gorini, G., Graham, M., Hellesen, C., Hellsten, T., Huygen, S., Jacquet, P., Johnson, T., Kiptily, V., Knipe, S., Krasilnikov, A., Lamalle, P., Lennholm, M., Loarte, A., Maggiora, R., Maslov, M., Messiaen, A., Milanesio, D., Monakhov, I., Nightingale, M., Noble, C., Nocente, M., Pangioni, L., Proverbio, I., Sozzi, C., Stamp, M., Studholme, W., Tardocchi, M., Versloot, T. W., Vdovin, V., Vrancken, M., Whitehurst, A., Wooldridge, E., Zoita, V., Lerche, E., Van Eester, D., Ongena, J., Mayoral, M-L, Laxaback, M., Rimini, F., Argouarch, A., Beaumont, P., Blackman, T., Bobkov, V., Brennan, D., Brett, A., Calabro, G., Cecconello, Marco, Coffey, I., Colas, L., Coyne, A., Crombe, K., Czarnecka, A., Dumont, R., Durodie, F., Felton, R., Frigione, D., Gatu Johnson, Maria, Giroud, C., Gorini, G., Graham, M., Hellesen, C., Hellsten, T., Huygen, S., Jacquet, P., Johnson, T., Kiptily, V., Knipe, S., Krasilnikov, A., Lamalle, P., Lennholm, M., Loarte, A., Maggiora, R., Maslov, M., Messiaen, A., Milanesio, D., Monakhov, I., Nightingale, M., Noble, C., Nocente, M., Pangioni, L., Proverbio, I., Sozzi, C., Stamp, M., Studholme, W., Tardocchi, M., Versloot, T. W., Vdovin, V., Vrancken, M., Whitehurst, A., Wooldridge, E., and Zoita, V.

Abstract

In the past years, one of the focal points of the JET experimental programme was on ion-cyclotron resonance heating (ICRH) studies in view of the design and exploitation of the ICRH system being developed for ITER. In this brief review, some of the main achievements obtained in JET in this field during the last 5 years will be summarized. The results reported here include important aspects of a more engineering nature, such as (i) the appropriate design of the RF feeding circuits for optimal load resilient operation and (ii) the test of a compact high-power density antenna array, as well as RF physics oriented studies aiming at refining the numerical models used for predicting the performance of the ICRH system in ITER. The latter include (i) experiments designed for improving the modelling of the antenna coupling resistance under various plasma conditions and (ii) the assessment of the heating performance of ICRH scenarios to be used in the non-active operation phase of ITER.

Published
2011
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27. Enhancing the mode conversion efficiency in JET plasmas with multiple mode conversion layers

Author

Van Eester, D., Lerche, E., Johnson, Thomas Joe, Hellsten, Torbjörn, Ongena, J., Mayoral, M. -L, Frigione, D., Sozzi, C., Calabro, G., Lennholm, M., Beaumont, P., Blackman, T., Brennan, D., Brett, A., Cecconello, M., Coffey, I., Coyne, A., Crombe, K., Czarnecka, A., Felton, R., Johnson, M. G., Giroud, C., Gorini, G., Hellesen, C., Jacquet, P., Kazakov, Y., Kiptily, V., Knipe, S., Krasilnikov, A., Lin, Y., Maslov, M., Monakhov, I., Noble, C., Nocente, M., Pangioni, L., Proverbio, I., Stamp, M., Studholme, W., Tardocchi, M., Versloot, T. W., Vdovin, V., Whitehurst, A., Wooldridge, E., Zoita, V., Van Eester, D., Lerche, E., Johnson, Thomas Joe, Hellsten, Torbjörn, Ongena, J., Mayoral, M. -L, Frigione, D., Sozzi, C., Calabro, G., Lennholm, M., Beaumont, P., Blackman, T., Brennan, D., Brett, A., Cecconello, M., Coffey, I., Coyne, A., Crombe, K., Czarnecka, A., Felton, R., Johnson, M. G., Giroud, C., Gorini, G., Hellesen, C., Jacquet, P., Kazakov, Y., Kiptily, V., Knipe, S., Krasilnikov, A., Lin, Y., Maslov, M., Monakhov, I., Noble, C., Nocente, M., Pangioni, L., Proverbio, I., Stamp, M., Studholme, W., Tardocchi, M., Versloot, T. W., Vdovin, V., Whitehurst, A., Wooldridge, E., and Zoita, V.

Abstract

The constructive interference effect described by Fuchs et al. [1] shows that the mode conversion and thereby the overall heating efficiency can be enhanced significantly when an integer number of fast wave wavelengths can be folded in between the high field side fast wave cutoff and the ion-ion hybrid layer(s) at which the ion Bernstein or ion cyclotron waves are excited. This effect was already experimentally identified in ( 3He)-D plasmas [2] and was recently tested in ( 3He)-H JET plasmas. The latter is an 'inverted' scenario, which differs significantly from the ( 3He)-D scenarios since the mode-conversion layer is positioned between the low field side edge of the plasma and the ion-cyclotron layer of the minority 3He ions (whereas the order in which a wave entering the plasma from the low field side encounters these layers is inverted in a 'regular' scenario), and because much lower 3He concentrations are needed to achieve the mode-conversion heating regime. The presence of small amounts of 4He and D in the discharges gave rise to an additional mode conversion layer on top of the expected one associated with 3He-H, which made the interpretation of the results more complex but also more interesting: Three different regimes could be distinguished as a function of X[ 3He], and the differing dynamics at the various concentrations could be traced back to the presence of these two mode conversion layers and their associated fast wave cutoffs. Whereas (1-D and 2-D) numerical modeling yields quantitative information on the RF absorptivity, recent analytical work by Kazakov [3] permits to grasp the dominant underlying wave interaction physics., QC 20140905

Published
2011
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28. Enhancing The Mode Conversion Efficiency In JET Plasmas With Multiple Mode Conversion Layers

Author

Van Eester, D, Lerche, E, Johnson, T, Hellsten, T, Ongena, J, Mayoral, M, Frigione, D, Sozzi, C, Calabro, G, Lennholm, M, Beaumont, P, Blackman, T, Brennan, D, Brett, A, Cecconello, M, Coffey, I, Coyne, A, Crombe, K, Czarnecka, A, Felton, R, Johnson, M, Giroud, C, Gorini, G, Hellesen, C, Jacquet, P, Kazakov, Y, Kiptily, V, Knipe, S, Krasilnikov, A, Lin, Y, Maslov, M, Monakhov, I, Noble, C, Nocente, M, Pangioni, L, Proverbio, I, Stamp, M, Studholme, W, Tardocchi, M, Versloot, T, Vdovin, V, Whitehurst, A, Wooldridge, E, Zoita, V, GORINI, GIUSEPPE, NOCENTE, MASSIMO, Zoita, V., Van Eester, D, Lerche, E, Johnson, T, Hellsten, T, Ongena, J, Mayoral, M, Frigione, D, Sozzi, C, Calabro, G, Lennholm, M, Beaumont, P, Blackman, T, Brennan, D, Brett, A, Cecconello, M, Coffey, I, Coyne, A, Crombe, K, Czarnecka, A, Felton, R, Johnson, M, Giroud, C, Gorini, G, Hellesen, C, Jacquet, P, Kazakov, Y, Kiptily, V, Knipe, S, Krasilnikov, A, Lin, Y, Maslov, M, Monakhov, I, Noble, C, Nocente, M, Pangioni, L, Proverbio, I, Stamp, M, Studholme, W, Tardocchi, M, Versloot, T, Vdovin, V, Whitehurst, A, Wooldridge, E, Zoita, V, GORINI, GIUSEPPE, NOCENTE, MASSIMO, and Zoita, V.

Abstract

The constructive interference effect described by Fuchs et al. [1] shows that the mode conversion and thereby the overall heating efficiency can be enhanced significantly when an integer number of fast wave wavelengths can be folded in between the high field side fast wave cutoff and the ion‐ion hybrid layer(s) at which the ion Bernstein or ion cyclotron waves are excited. This effect was already experimentally identified in (3He)‐D plasmas [2] and was recently tested in (3He)‐H JET plasmas. The latter is an ‘inverted’ scenario, which differs significantly from the (3He)‐D scenarios since the mode‐conversion layer is positioned between the low field side edge of the plasma and the ion‐cyclotron layer of the minority 3He ions (whereas the order in which a wave entering the plasma from the low field side encounters these layers is inverted in a ‘regular’ scenario), and because much lower 3He concentrations are needed to achieve the mode‐conversion heating regime. The presence of small amounts of 4He and D in the discharges gave rise to an additional mode conversion layer on top of the expected one associated with 3He‐H, which made the interpretation of the results more complex but also more interesting: Three different regimes could be distinguished as a function of X[3He], and the differing dynamics at the various concentrations could be traced back to the presence of these two mode conversion layers and their associated fast wave cutoffs. Whereas (1‐D and 2‐D) numerical modeling yields quantitative information on the RF absorptivity, recent analytical work by Kazakov [3] permits to grasp the dominant underlying wave interaction physics.

Published
2011

29. Optimizing ion-cyclotron resonance frequency heating for ITER: dedicated JET experiments

Author

Lerche, E, Van Eester, D, Ongena, J, Mayoral, M, Laxaback, M, Rimini, F, Argouarch, A, Beaumont, P, Blackman, T, Bobkov, V, Brennan, D, Brett, A, Calabro, G, Cecconello, M, Coffey, I, Colas, L, Coyne, A, Crombe, K, Czarnecka, A, Dumont, R, Durodie, F, Felton, R, Frigione, D, Gatu Johnson, M, Giroud, C, Gorini, G, Graham, M, Hellesen, C, Hellsten, T, Huygen, S, Jacquet, P, Johnson, T, Kiptily, V, Knipe, S, Krasilnikov, A, Lamalle, P, Lennholm, M, Loarte, A, Maggiora, R, Maslov, M, Messiaen, A, Milanesio, D, Monakhov, I, Nightingale, M, Noble, C, Nocente, M, Pangioni, L, Proverbio, I, Sozzi, C, Stamp, M, Studholme, W, Tardocchi, M, Versloot, T, Vdovin, V, Vrancken, M, Whitehurst, A, Wooldridge, E, Zoita, V, JET EFDA, C, Mayoral, ML, Versloot, TW, JET EFDA contributors, GORINI, GIUSEPPE, NOCENTE, MASSIMO, Lerche, E, Van Eester, D, Ongena, J, Mayoral, M, Laxaback, M, Rimini, F, Argouarch, A, Beaumont, P, Blackman, T, Bobkov, V, Brennan, D, Brett, A, Calabro, G, Cecconello, M, Coffey, I, Colas, L, Coyne, A, Crombe, K, Czarnecka, A, Dumont, R, Durodie, F, Felton, R, Frigione, D, Gatu Johnson, M, Giroud, C, Gorini, G, Graham, M, Hellesen, C, Hellsten, T, Huygen, S, Jacquet, P, Johnson, T, Kiptily, V, Knipe, S, Krasilnikov, A, Lamalle, P, Lennholm, M, Loarte, A, Maggiora, R, Maslov, M, Messiaen, A, Milanesio, D, Monakhov, I, Nightingale, M, Noble, C, Nocente, M, Pangioni, L, Proverbio, I, Sozzi, C, Stamp, M, Studholme, W, Tardocchi, M, Versloot, T, Vdovin, V, Vrancken, M, Whitehurst, A, Wooldridge, E, Zoita, V, JET EFDA, C, Mayoral, ML, Versloot, TW, JET EFDA contributors, GORINI, GIUSEPPE, and NOCENTE, MASSIMO

Abstract

In the past years, one of the focal points of the JET experimental programme was on ion-cyclotron resonance heating (ICRH) studies in view of the design and exploitation of the ICRH system being developed for ITER. In this brief review, some of the main achievements obtained in JET in this field during the last 5 years will be summarized. The results reported here include important aspects of a more engineering nature, such as (i) the appropriate design of the RF feeding circuits for optimal load resilient operation and (ii) the test of a compact high-power density antenna array, as well as RF physics oriented studies aiming at refining the numerical models used for predicting the performance of the ICRH system in ITER. The latter include (i) experiments designed for improving the modelling of the antenna coupling resistance under various plasma conditions and (ii) the assessment of the heating performance of ICRH scenarios to be used in the non-active operation phase of ITER. © 2011 IOP Publishing Ltd.

Published
2011

30. Potential of the ICRH schemes in H-(3He) plasmas proposed for ITER?s half-field non-activated phase

Author

Lerche, E., Van Eester, D., Johnson, Thomas, Hellsten, Torbjörn, Ongena, J., Mayoral, M.-L., Frigione, D., Sozzi, C., Calabro, G., Lennholm, M., Beaumont, P., Blackman, T., Brennan, D., Brett, A., Cecconello, M., Coffey, I., Coyne, A., Crombe, K., Czarnecka, A., Felton, R., Giroud, C., Gatu Johnson, M., Gorini, G., Hellesen, C., Jacquet, P., Kiptily, V., Knipe, S., Krasilnikov, A., Maslov, M., Messiaen, A., Monakhov, I., Noble, C., Nocente, M., Pangioni, L., Proverbio, I., Stamp, M., Studholme, W., Tardocchi, M., Versloot, T., Vdovin, V., Whitehurst, A., Wooldridge, E., Zoita, V., Lerche, E., Van Eester, D., Johnson, Thomas, Hellsten, Torbjörn, Ongena, J., Mayoral, M.-L., Frigione, D., Sozzi, C., Calabro, G., Lennholm, M., Beaumont, P., Blackman, T., Brennan, D., Brett, A., Cecconello, M., Coffey, I., Coyne, A., Crombe, K., Czarnecka, A., Felton, R., Giroud, C., Gatu Johnson, M., Gorini, G., Hellesen, C., Jacquet, P., Kiptily, V., Knipe, S., Krasilnikov, A., Maslov, M., Messiaen, A., Monakhov, I., Noble, C., Nocente, M., Pangioni, L., Proverbio, I., Stamp, M., Studholme, W., Tardocchi, M., Versloot, T., Vdovin, V., Whitehurst, A., Wooldridge, E., and Zoita, V.

Abstract

NQC

Published
2010

31. Mode conversion heating in JET plasmas with multiple mode conversion layers

Author

Van Eester, D., Lerche, E., Johnson, Thomas, Hellsten, Torbjörn, Ongena, J., Mayoral, M. -L, Frigione, D., Sozzi, C., Calabro, G., Lennholm, M., Beaumont, P., Blackman, T., Brennan, D., Brett, A., Cecconello, M., Coffey, I., Coyne, A., Crombe, K., Czarnecka, A., Felton, R., Gatu Johnson, M., Giroud, C., Gorini, G., Hellesen, C., Jacquet, P., Kazakov, Y., Kiptily, V., Knipe, S., Krasilnikov, A., Lin, Y., Maslov, M., Monakhov, I., Noble, C., Nocente, M., Pangioni, L., Proverbio, I., Stamp, M., Studholme, W., Tardocchi, M., Versloot, T. W., Vdovin, V., Whitehurst, A., Wooldridge, E., Zoita, V., Van Eester, D., Lerche, E., Johnson, Thomas, Hellsten, Torbjörn, Ongena, J., Mayoral, M. -L, Frigione, D., Sozzi, C., Calabro, G., Lennholm, M., Beaumont, P., Blackman, T., Brennan, D., Brett, A., Cecconello, M., Coffey, I., Coyne, A., Crombe, K., Czarnecka, A., Felton, R., Gatu Johnson, M., Giroud, C., Gorini, G., Hellesen, C., Jacquet, P., Kazakov, Y., Kiptily, V., Knipe, S., Krasilnikov, A., Lin, Y., Maslov, M., Monakhov, I., Noble, C., Nocente, M., Pangioni, L., Proverbio, I., Stamp, M., Studholme, W., Tardocchi, M., Versloot, T. W., Vdovin, V., Whitehurst, A., Wooldridge, E., and Zoita, V.

Abstract

QC 20140814

Published
2010

32. Overview of Recent Results on Heating and Current Drive in the JET tokamak

Author

Mayoral, M. -L, Ongena, J., Argouarch, A., Baranov, Yu., Blackman, T., Bobkov, V., Budny, R., Colas, L., Czarnecka, A., Delpech, L., Durodie, F., Ekedahl, A., Gauthier, M., Goniche, M., Goulding, R., Graham, M., Hillairet, J., Huygen, S., Jacquet, Ph., Johnson, Thomas J., Kiptily, V., Kirov, K., Laxåback, Martin, Lerche, E., Mailloux, J., Monakhov, I., Nave, M. F. F., Nightingale, M., Plyusnin, V., Petrzilka, V., Rimini, F., Van Eester, D., Whitehurst, A., Wooldridge, E., Vrancken, M., Mayoral, M. -L, Ongena, J., Argouarch, A., Baranov, Yu., Blackman, T., Bobkov, V., Budny, R., Colas, L., Czarnecka, A., Delpech, L., Durodie, F., Ekedahl, A., Gauthier, M., Goniche, M., Goulding, R., Graham, M., Hillairet, J., Huygen, S., Jacquet, Ph., Johnson, Thomas J., Kiptily, V., Kirov, K., Laxåback, Martin, Lerche, E., Mailloux, J., Monakhov, I., Nave, M. F. F., Nightingale, M., Plyusnin, V., Petrzilka, V., Rimini, F., Van Eester, D., Whitehurst, A., Wooldridge, E., and Vrancken, M.

Abstract

In this paper, significant results in the heating and current drive domains obtained at JET in the past few years following systems upgrade and dedicated experimental time, will be reviewed. Firstly, an overview of the new Ion Cyclotron Resonance Frequency (ICRF) heating capabilities will be presented i.e. results from the ITER-Like ICRF antenna (ILA), the use of External Conjugate-T and 3dB hybrid couplers to increase the ICRF power during ELMy H-mode, Furthermore, experiments to study the influence of the phasing of the ICRF antenna on power absorption and coupling will be described. Looking at Low Hybrid (I-H) issues for ITER, the effect of the location of gas injection on the LH coupling improvement at large launcher-separatrix distances will be discussed as the possibility to operate at ITER-relevant power densities. Experiments to characterise the LH power losses in the Scrape-Off-Layer (SOL) and to determine the LH wave absorption and current drive using power modulation will be shown. Finally, plasma rotation studies in the presence of ICRF heating with standard and enhanced JET toroidal field ripple will be presented., QC 20101118

Published
2009
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34. FWCD Technology Issues for DEMO.

Author

Nightingale, M., Wooldridge, E., and Monakhov, I.

Subjects
*CURRENT-drive heating, *RESISTANCE heating, *WAVEGUIDES, *PHYSICS, *PLASMA physics, *PLASMA currents, *PLASMA power sources
Abstract

The technology implications of potential FWCD systems have been assessed at two frequencies of relevance to DEMO as part of a wider study of heating and current drive systems for the EFDA Power Plant Physics and Technology (PPP&T), based upon two reference DEMO designs. Using the results of Van Eester et al [1], systems studies carried out for a 62MHz mid-harmonic system mounted on a 23MA 5.74T 8.5m major radius DEMO suggested that antenna voltages close to 50kV, and the handling of the resultant sheath power loadings, are likely to be required if all of the 12.9MA non-bootstrap current drive is to be provided by FWCD. The "wall plug" electrical efficiency of the midharmonic option of 0.18A/W.m², potentially rising to 0.23A/W.m² with the future development of solid state generators, however, looks very attractive, and the coupling is less sensitive to plasma edge parameters than for existing antennas, due to the low k// of 2.8m-1. The design could be based upon that presently under consideration for ITER, except for the replacement of insulating vacuum windows located relatively close to the plasma with all-metal designs [2]. A 352MHz high-harmonic option also looks technologically feasible, using a waveguide-based design and a port plug layout has been provided. This option might bring sheath effect and voltage hold-off benefits, but this is far from proven. In this case, systems studies were not feasible due to a lack of firm results from the physics studies. For both options: (a) the RF generators, power supplies and transmission line components required are either already available, or are under development for ITER, and (b) mechanical and material issues associated with the proposed FWCD antenna structures appear challenging, but will need solving on a wider basis across DEMO. [ABSTRACT FROM AUTHOR]

Published
2014
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35. Optimizing ion-cyclotron resonance frequency heating for ITER: dedicated JET experiments

Author

Lerche, E, primary, Van Eester, D, additional, Ongena, J, additional, Mayoral, M-L, additional, Laxaback, M, additional, Rimini, F, additional, Argouarch, A, additional, Beaumont, P, additional, Blackman, T, additional, Bobkov, V, additional, Brennan, D, additional, Brett, A, additional, Calabro, G, additional, Cecconello, M, additional, Coffey, I, additional, Colas, L, additional, Coyne, A, additional, Crombe, K, additional, Czarnecka, A, additional, Dumont, R, additional, Durodie, F, additional, Felton, R, additional, Frigione, D, additional, Gatu Johnson, M, additional, Giroud, C, additional, Gorini, G, additional, Graham, M, additional, Hellesen, C, additional, Hellsten, T, additional, Huygen, S, additional, Jacquet, P, additional, Johnson, T, additional, Kiptily, V, additional, Knipe, S, additional, Krasilnikov, A, additional, Lamalle, P, additional, Lennholm, M, additional, Loarte, A, additional, Maggiora, R, additional, Maslov, M, additional, Messiaen, A, additional, Milanesio, D, additional, Monakhov, I, additional, Nightingale, M, additional, Noble, C, additional, Nocente, M, additional, Pangioni, L, additional, Proverbio, I, additional, Sozzi, C, additional, Stamp, M, additional, Studholme, W, additional, Tardocchi, M, additional, Versloot, T W, additional, Vdovin, V, additional, Vrancken, M, additional, Whitehurst, A, additional, Wooldridge, E, additional, Zoita, V, additional, and EFDA Contributors, JET, additional

Published
2012
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36. The Design, Verification, and Performance of the James Webb Space Telescope

Author

Menzel, M., Davis, M., Parrish, K., Lawrence, J., Stewart, A., Cooper, J., Irish, S., Mosier, G., Levine, M., Pitman, J., Walsh, G., Maghami, P., Thomson, S., Wooldridge, E., Boucarut, R., Feinberg, L., Turner, G., Kalia, P., and Bowers, C.

Abstract

The James Webb Space Telescope (JWST) is NASA’s flagship mission successor to the highly successful Hubble Space Telescope. It is an infrared observatory featuring a cryogenic 6.6 m aperture, deployable Optical Telescope Element (OTE) with a payload of four science instruments (SIs) assembled into an Integrated Science Instrument Module (ISIM) that provide imagery and spectroscopy in the near-infrared band between 0.6 and 5 μm and in the mid-infrared band between 5 and 28.1 μm. JWST was successfully launched on 2021 December 25 aboard an Ariane 5 launch vehicle. All 50 major deployments were successfully completed on 2022 January 8. The observatory performed all midcourse correction maneuvers and achieved its operational mission orbit around the Sun–Earth second Lagrange point (L2). All commissioning and calibration activities have been completed, and JWST has begun its science mission. This paper will provide a description of the driving requirements and their technical challenges, the engineering processes involved in the design formulation, the resulting observatory design, the verification programs that proved it to be flightworthy, and the measured on-orbit performance of the observatory. Since companion papers will describe the details of the OTE and SIs, this paper will concentrate on describing the key features of the observatory architecture that accommodates these elements, particularly those features and capabilities associated with accommodating the radiometric and image-quality performance.

Published
2023
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38. Proposal of an Arc Detection Technique Based on RF Measurements for the ITER ICRF Antenna.

Author

Huygen, S., Dumortier, P., Durodié, F., Messiaen, A., Vervier, M., Vrancken, M., and Wooldridge, E.

Subjects
ELECTRIC arc, RADIO frequency, FUSION reactors, ION cyclotron resonance spectrometry, ANTENNAS (Electronics), NUCLEAR engineering safety measures, SIMULATION methods & models
Abstract

RF arc detection is a key operational and safety issue for the ICRF system on ITER. Indeed the high voltages inside the antenna put it at risk of arcing, which could cause substantial damage. This paper describes the various possibilities explored by circuit simulation and the strategy now considered to protect the ITER ICRF antenna from RF arcs. [ABSTRACT FROM AUTHOR]

Published
2011
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39. Design of the ITER ICRF Antenna.

Author

Hancock, D., Nightingale, M., Bamber, R., Dalton, N., Durodie, F., Firdaouss, M., Lister, J., Porton, M., Shannon, M., Wilson, D., Winkler, K., and Wooldridge, E.

Subjects
FUSION reactors, NUCLEAR reactor design & construction, ION cyclotron resonance spectrometry, ANTENNAS (Electronics), CONSORTIA, MECHANICAL engineering, MATHEMATICAL optimization, ENGINEERING design
Abstract

The CYCLE consortium has been designing the ITER ICRF antenna since March 2010, supported by an F4E grant. Following a brief introduction to the consortium, this paper: describes the present status and layout of the design; highlights the key mechanical engineering features; shows the expected impact of cooling and radiation issues on the design and outlines the need for future R&D to support the design process. A key design requirement is the need for the mechanical design and analysis to be consistent with all requirements following from the RF physics and antenna layout optimisation. As such, this paper complements that of Durodie et al [1]. [ABSTRACT FROM AUTHOR]

Published
2011
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41. Present Status of the ITER-like ICRF Antenna on JET.

Author

Durodié, F., Nightingale, M., Mayoral, M.-L., Argouarch, A., Blackman, T., Gauthier, M., Goulding, R., Graham, M., Huygen, S., Jacquet, P., Lerche, E., Ongena, J., Van Eester, D., Vrancken, M., Whitehurst, A., and Wooldridge, E.

Subjects
ION cyclotron resonance spectrometry, ANTENNAS (Electronics), PLASMA gases, INTEGRATED circuits, ELECTRIC power systems
Abstract

The commissioning of the ITER-Like ICRF Antenna (ILA) [1] on JET plasmas from May 2008 to April 2009 in various conditions (33, 42 and 47 MHz, L- and H-mode, antenna strap-plasma separatrix distances of ∼9 to 17 cm) has provided relevant information for future antenna design and operation. The maximum power density achieved was 6.2 MW/m2 in L-mode with strap to plasma separatrix distance of ∼9–10 cm at 42 MHz on the lower half of the ILA extrapolating to 8 MW/m2 if the full generator power had been available. Efficient (trip-free operation) ELM tolerance was obtained both at 33 and 42 MHz on a large range of ELMs with strap voltages up to 42 kV and a maximum power density of 4.1 MW/m2. The paper reviews these achievements as well as remaining issues. [ABSTRACT FROM AUTHOR]

Published
2009
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42. Simulating the JET ITER-like Antenna circuit.

Author

Van Eester, D., Lerche, E., Argouarch, A., Blackman, T., Durodie, F., Evrard, M., Goulding, R. H., Huygen, S., Jacquet, P., Mayoral, M.-L., Monakhov, I., Nightingale, M., Ongena, J., Vrancken, M., Wooldridge, E., and Whitehurst, A.

Subjects
ANTENNAS (Electronics), INTEGRATED circuits, SIMULATION methods & models, IMPEDANCE matrices, RADIO frequency
Abstract

A set of simulation/interpretation tools based on transmission line theory and on the RF model developed by M. Vrancken [2] has been developed to study the ITER-like Antenna (ILA) at JET. For given tuning element settings, the unique solution of the equations governing the ILA circuit requires solving a system of coupled linear equations relating the voltages and currents at the antenna straps and other key locations. This computation allows cross-checking predicted values against measured experimental ones. Further more, a minimization procedure allows improving the correspondence with the quantities measured in the circuit during shots, thus coping with unavoidable errors arising from uncertainties in the measurements or from inaccuracies in the adopted RF model. Typical applications are e.g. fine-tuning of the second-stage of the ILA circuit for increased ELM-resilience, cross-checking the calibration of the measurements throughout the circuit and predicting the antenna performance and matching conditions in new plasma scenarios. [ABSTRACT FROM AUTHOR]

Published
2009
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43. Design and operations of a load-tolerant external conjugate-T matching system for the A2 ICRH antennas at JET.

Author

Monakhov, I., Graham, M., Blackman, T., Dowson, S., Durodie, F., Jacquet, P., Lehmann, J., Mayoral, M. -L., Nightingale, M. P. S., Noble, C., Sheikh, H., Vrancken, M., Walden, A., Whitehurst, A., and Wooldridge, E.

Subjects
ICR heating, RADIO frequency, SIMULATION methods & models, PLASMA jets, ALGORITHMS
Abstract

A load-tolerant external conjugate-T (ECT) impedance matching system for two A2 ion cyclotron resonance heating (ICRH) antennas was successfully put into operation at JET. The system allows continuous injection of the radio-frequency (RF) power into plasma in the presence of strong antenna loading perturbations caused by edge-localized modes (ELMs). Reliable ECT performance was demonstrated under a variety of antenna loading conditions including H-mode plasmas with radial outer gaps (ROGs) in the range 4-14 cm. The high resilience to ELMs predicted during the circuit simulations was fully confirmed experimentally. Dedicated arc-detection techniques and real-time matching algorithms were developed as a part of the ECT project. The new advanced wave amplitude comparison system has proven highly efficient in detection of arcs both between and during ELMs. The ECT system has allowed the delivery of up to 4 MW of RF power without trips into plasmas with type-I ELMs. Together with the 3 dB system and the ITER-like antenna, the ECT has brought the total RF power coupled to ELMy plasma to over 8 MW, considerably enhancing JET research capabilities. This paper provides an overview of the key design features of the ECT system and summarizes the main experimental results achieved so far. [ABSTRACT FROM AUTHOR]

Published
2013
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44. Implementation of load resilient ion cyclotron resonant frequency (ICRF) systems to couple high levels of ICRF power to ELMy H-mode plasmas in JET.

Author

Graham, M., Mayoral, M-L., Monakhov, I., Ongena, J., Blackman, T., Nightingale, M. P. S., Wooldridge, E., Durodié, F., Argouarch, A., Berger-By, G., Czarnecka, A., Dowson, S., Goulding, R., Huygen, S., Jacquet, P., Wade, T. J., Lerche, E., Lamalle, P. U., Sheikh, H., and Van Eester, D.

Subjects
ION sources, HYDROGEN plasmas, JETS (Nuclear physics), POWER density, COMPARATIVE studies, MECHANICAL loads
Abstract

The paper summarizes the continuous developments made to the ion cyclotron resonant frequency (ICRF) system at JET in order to improve the reliability of the power coupled to plasma. It details the changes and improvements made to the system so that more power is coupled during ELMy plasmas as well as increasing the power density to demonstrate reliable operation in the range of the requirements for ITER. Results obtained using the conventional matching (stubs and trombones) system, 3 dB couplers and the conjugate-T scheme with variable matching elements outside the wave launching structure (external conjugate-T) and inside the wave launching structure (ITER-like antenna) are described. The presence of the three different approaches to load resilient ICRF systems at JET creates a unique opportunity to compare these methods under very similar plasma conditions and to assess the results of ICRF power delivery to ELMy plasmas, an important issue for ITER. The impact of the availability of increased levels of reliable ICRF power on plasma physics studies in JET is illustrated. [ABSTRACT FROM AUTHOR]

Published
2012
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45. JET ICRH Plant Statistics from 2008-2012.

Author

Wooldridge, E., Monakhov, I., Blackman, T., Gibson, C., Graham, M., Jacquet, P., Lerche, E., and Noble, C.

Subjects
*ICR heating, *HIGH-frequency heating, *PLASMA engineering, *PLASMA devices, *PLASMA physics
Abstract

JET ICRH plant faults from 2008 - 2012 have been catalogued and a new assessment of the reliability of the plant by sub-system is given. Data from pulses where ICRH was used, excluding the ITER-Like Antenna (ILA) and its generators, has been collated. This is compared to fault data in order to investigate any correlation between faults and operations. The number of faults is shown to have decreased between 2011-2012 in comparison to 2008-2009 as the time between faults is shown to have increased. Future electronic fault logging requirements to enable easier analysis are discussed. Due to the changing configuration of the ICRH plant; the introduction of ELM tolerant systems, generator upgrade, changes to the settings of the VSWR protection et cetera, a method to expand the fault database to include more historical data [1] in a consistent way are discussed. [ABSTRACT FROM AUTHOR]

Published
2014
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47. Snapshots from the First Century of Naval Aviation.

Author

Wooldridge, E. T.

Subjects
*PHOTOGRAPHS, *NAVAL aviation
Abstract

Several photographs related to the U.S. naval aviation are presented, including one showing Astronaut Alan B. Shepard on the USS Lake Champlain (CVS-39), one showing the first female airpilot Lieutenant Barbara Ann Allen, and one showing the first helicopter Sikorsky HNS-1 in October 1943.

Published
2011

48. Flight from the Sea.

Author

Wooldridge, E. T.

Subjects
*NAVAL aviation, HISTORY of the United States Navy
Abstract

As the United States celebrates the 100th anniversary of Orville Wright's first flight at Kitty Hawk, North Carolina, "Naval History," highlights the heritage of the U.S. naval flight with selected images from the aviation collection of the U.S. Naval Institute Photo Archives. Although the official birthday of the U.S. naval aviation is May 8, 1911, the U.S. Navy showed early interest in aviation in 1898, when an interservice board was formed to investigate the military possibilities of Samuel P. Langley's Aerodrome flying machines. Shortly thereafter, on November 14, 1910, Eugene Ely took off successfully from the warship USS Birmingham (CL-2), anchored in Hampton Roads, Virginia. Other historic events followed in quick succession. Lieutenant T. G. Ellyson reported for flight training as Naval Aviator Number One and was a key figure in demonstrating the Navy's first airplane, the Curtiss A-1. Years leading to the U.S. entry into World War 1 were marked by significant progress in the Navy's efforts to take aviation to sea. These revolutionary changes are documented thoroughly in the Naval Institute's naval aviation collection. The golden age photographs collection is an eclectic mix of photographs from aircraft manufacturers, official U.S. Navy sources, the National Archives, private collections and professional aviation photographers and collectors.

Published
2003

49. `You Can't Handle the Truth!'.

Author

Wooldridge, E. Tyler

Subjects
*READER-response criticism, *EMPLOYEE attitudes, *CORPORATE culture
Abstract

Focuses on the controversy generated by the article `A Tale of Two Cities' in the July 1999 issue of the United States Naval Institute Proceedings journal. View of Navy senior leadership on internal criticism as disloyal; Intimidations from Navy officers; Skepticism over the system's responsiveness to criticism by respected officers.

Published
2000

50. EMMA - The world's first non-scaling FFAG

Author

Edgecock, R., David Kelliher, Machida, S., Beard, C., Bliss, N., Clarke, J., Hill, C., Jamison, S., Kalinin, A., Marinov, K., Marks, N., Martlew, B., Mcintosh, P., Muratori, B., Owen, H., Saveliev, Y., Shepherd, B., Smith, R., Smith, S., Tzenov, S., White, C., Wooldridge, E., Berg, J. S., Trbojevic, D., Craddock, M., Koscielniak, S., Crisp, J., Johnstone, C., Giboudot, Y., Keil, E., Méot, F., Yokoi, T., European Organization for Nuclear Research (CERN), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.PHYS.PHYS-ACC-PH]Physics [physics]/Physics [physics]/Accelerator Physics [physics.acc-ph]
Abstract

International audience; EMMA – the Electron Model of Many Applications – is to be built at the STFC Daresbury Laboratory in the UK and will be the first non-scaling FFAG ever constructed. EMMA will be used to demonstrate the principle of this type of accelerator and study its features in detail. The design of the machine and its hardware components are now far advanced and construction is due for completion in Autumn 2009.

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