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Your search keyword '"Lemke, R.W."' showing total 123 results
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123 results on '"Lemke, R.W."'

3. Magnetically accelerated, ultrahigh velocity flyer plates for shock wave experiments

Author

Lemke, R.W., Knudson, M.D., Bliss, D.E., Cochrane, K., Davis, J.-P., Giunta, A.A., Harjes, H.C., and Slutz, S.A.

Subjects
Shock waves -- Analysis, Magnetohydrodynamics -- Analysis, Aluminum compounds -- Acoustic properties, Physics
Abstract

Magnetohydrodynamic simulations that are used to optimize the magnetic pressure for a given flyer load and to determine the shape of the current rise time are discussed. Results pertaining to plate impact, shock wave experiments in which the aluminum flyer plates are magnetically accelerated across a vacuum gap and impact z-cut, alpha-quartz targets are presented.

Published
2005

5. Increasing the RF energy per pulse of an RKO

Author

Hendricks, K.J., Haworht, M.D., Englert, T., Shiffler, Don, Baca, G., Coleman, P.D., Bowers, L., Lemke, R.W., Spencer, Thomas A., and Arman, M. Joseph

Subjects
Klystrons -- Research, Microwaves -- Research, Radio -- Energy use, Microwave oscillators -- Energy use, Business, Chemistry, Electronics, Electronics and electrical industries
Abstract

The Air Force Research Laboratory RKO source has recently demonstrated the ability to convert electron beam power to Rf power until the termination of the electron beam pulse, achieving a power of 1.5 GW at an energy of 170 J. These results represent an increase in power of 25-30% in power and energy extracted from this source. This paper discusses the principal research areas encountered in lengthening the RF pulse (FWHM) from 50 ns to the present 120 ns and the associated increase in the RF energy. Index Terms - Gigawatt, klystron, microwave, RF, RKO.

Published
1998

6. Significant pulse-lengthening in a multigigawatt magnetically insulated transmission line oscillator

Author

Haworth, M.D., Baca, G., Benford, James N., Englert, T., Hackett, K., Hendricks, K.J., Henley, D., LaCour, M., Lemke, R.W., Price, David, Ralph, D., Sena, M., Shiffler, Don, and Spencer, Thomas A.

Subjects
Microwave transmission lines -- Research, Microwave tubes -- Research, Pulse-duration modulation -- Research, Business, Chemistry, Electronics, Electronics and electrical industries
Abstract

The Air Force Research Laboratory/Phillips Laboratory magnetically insulated transmission line oscillator (MILO) is a gigawatt-class, L-band, high-power microwave tube driven by a 500-kV, 60-kA electron beam. A previous version of this tube [1] generated 1.5 GW pulses, but with significant RF pulse shortening. This paper reports on improvements to the tube that have allowed us to increase the output power by 25% and to increase the RF pulse duration by a factor of two and a half. Index Terms - Crossed-field device, high-power microwave tube, magnetically insulated transmission line oscillator, MILO.

Published
1998

7. Near-absolute Hugoniot measurements in aluminum to 500 GPa using a magnetically accelerated flyer plate technique

Author

Knudson, M.D., Lemke, R.W., Hayes, D.B., Hall, A.C., Deeney, C., and Asay, J.R.

Subjects
Strains and stresses -- Research, Aluminum -- Research, Physics
Abstract

A magnetically accelerated flyer plate technique is used when Hugonoit measurements are performed on aluminum in the stress range 100-500. The improved accuracy lends increased confidence to the use of aluminum as a standard material in future impedance matching experiments and enhances the understanding of the response of aluminum to 500GPa.

Published
2003

10. Status of genesis a 5 MA programmable pulsed power driver

Author

Glover, S.F., primary, White, F.E., additional, Foster, P.J., additional, Lucero, D.J., additional, Schneider, L.X., additional, Reed, K.W., additional, Pena, G.E., additional, Davis, J.-P., additional, Hall, C.A., additional, Hickman, R.J., additional, Hodge, K.C., additional, Lemke, R.W., additional, Lehr, J.M., additional, McDaniel, D.H., additional, Puissant, J. G., additional, Rudys, J.M., additional, Sceiford, M.E., additional, Tullar, S.J., additional, and Van De Valde, D.M., additional

Published
2011
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12. Impact of time-varying loads on the programmable pulsed power driver called genesis

Author

Glover, S.F., primary, Davis, J.-P., additional, Schneider, L.X., additional, Reed, K.W., additional, Pena, G.E., additional, Hall, C.A., additional, Hanshaw, H.L., additional, Hickman, R.J., additional, Hodge, K.C., additional, Lemke, R.W., additional, Lehr, J.M., additional, Lucero, D.J., additional, McDaniel, D.H., additional, Puissant, J. G., additional, Rudys, J.M., additional, Sceiford, M.E., additional, Tullar, S.J., additional, Van De Valde, D.M., additional, White, F.E., additional, Warne, L. K., additional, Coats, R. S., additional, and Johnson, W. A., additional

Published
2011
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29. Three-dimensional particle-in-cell simulation study of a relativistic magnetron.

Author

Lemke, R.W. and Genoni, T.C.

Subjects
*MAGNETRONS, *RELATIVISTIC mechanics, *MAGNETIC fields
Abstract

Investigates the A6 (six cavity) magnetron operated at relativistic voltages using a three-dimensional particle-in-cell simulation. Mode control; Causes and prevention of leakage current; Voltage scaling; Functional dependence of operating voltage on applied magnetic field.

Published
1999
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30. Frequency and power response of high-power plasma-filled backward-wave oscillators.

Author

Goebel, D. M., Ponti, E. S., Eisenhart, R.L., and Lemke, R.W.

Subjects
BACKWARD-wave tubes, ELECTRIC oscillators, PLASMA gases
Abstract

Examines the frequency and power response of high-power plasma-filled backward-wave oscillators (BWO). Determination of frequency of BWO by the circuit geometry and the electron beam parameters; End reflections in low-loss circuit designs and excessive plasma generation.

Published
1999
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31. Ion divergence in magnetically insulated diodes.

Author

Slutz, S.A., Lemke, R.W., Pointon, T.D., Desjarlais, M.P., Johnson, D.J., Mehlhorn, T.A., Filuk, A., and Bailey, J.

Subjects
*PHYSICAL & theoretical chemistry, *DIODES, *ION bombardment, *IONS, *MAGNETIC fields, *ELECTRONS, *PHYSICS, *PHYSICAL sciences
Abstract

Magnetically insulated ion diodes are being developed to drive inertial confinement fusion. Ion beam microdivergence must be reduced to achieve the very high beam intensities required to achieve this goal. Three-dimensional particle-in-cell simulations [Phys. Rev. Lett. 67, 3094 (1991)] indicate that instability-induced fluctuations can produce significant ion divergence during acceleration. These simulations exhibit a fast growing mode early in time, which has been identified as the diocotron instability. The divergence generated by this mode is modest, due to the relatively high-frequency (>1 GHz). Later, a low-frequency low-phase-velocity instability develops with a frequency that is approximately the reciprocal of the ion transit time. This instability couples effectively to the ions, and can generate unacceptably large ion divergences (>30 mrad). Linear stability theory reveals that this mode has structure parallel to the applied magnetic field and is related to the modified two-stream instability. Measurements of ion density fluctuations and energy-momentum correlations have confirmed that instabilities develop in ion diodes and contribute to the ion divergence. In addition, spectroscopic measurements indicate that lithium ions have a significant transverse temperature very close to the emission surface. Passive thin-film lithium fluoride (LiF) anodes have larger transverse beam temperatures than laser-irradiated active sources. Calculations of the ion beam source divergence for the LiF film due to surface roughness and the possible loss of adhesion and fragmentation of this film are presented.. [ABSTRACT FROM AUTHOR]

Published
1996
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32. A full mode set electromagnetic stability analysis of magnetically insulated ion diodes.

Author

Lemke, R.W. and Slutz, S.A.

Subjects
*DIODES, *ELECTROMAGNETISM, *ELECTROMAGNETIC fields
Abstract

Analyzes the stability of magnetically insulated ion diodes which includes electromagnetic perturbations both parallel and perpendicular to the applied magnetic field. Modified two-stream instability; Fast growing, low-phase velocity mode; Low frequency mode observed in three-dimensional particle simulations; Ion divergence.

Published
1995
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34. Georgia mica mines

Author

Heinrich, E.W., primary, Lemke, R.W., additional, Klepper, M.R., additional, Pray, L.C., additional, Allen, W.B., additional, and Jahns, R.H., additional

Published
1944
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35. North Carolina mica mines

Author

Olson, J.C., primary, Seegers, L.W., additional, Parker, J.W., additional, Goldthwait, L., additional, Parker, J. W., additional, Fryklund, V.C., additional, Griffitts, W.R., additional, Norman, L.A., additional, Stoll, W.C., additional, Jahns, R.J., additional, Irwin, W.P., additional, Lancaster, Paul, additional, Klepper, M.R., additional, Heinrich, E.W., additional, Pray, L.C., additional, Larrabee, D.W., additional, Swanson, R.A., additional, Allen, W.B., additional, Page, J.J., additional, Ellingwood, E., additional, Wolfe, J.R., additional, Lemke, R.W., additional, and Miller, R., additional

Published
1944
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36. Virginia mica mines

Author

Lemke, R.W., primary, Stillwell, J.H., additional, Smith, R.L., additional, Ellingwood, E., additional, Jahns, R.H., additional, and Miller, R., additional

Published
1944
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39. North Carolina mica mines

Author

Hustad, J.B., primary, Lemke, R.W., additional, Parker, J. M., additional, Griffitts, W.R., additional, Wolfe, J.R., additional, Heinrich, E.W., additional, Hadley, J.B., additional, and Irwin, W.P., additional

Published
1945
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49. Multi-dimensional Z-pinch calculations with ALEGRA

Author

Haill, T.A., primary, Brunner, T.A., additional, Budge, K.G., additional, Desjarlais, M.P., additional, Garasi, C.J., additional, Lawrence, R.J., additional, Lemke, R.W., additional, Mehlhorn, T.A., additional, Robinson, A.C., additional, and Cochrane, K., additional

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50. Multi-dimensional z-pinch calculations with ALEGRA

Author

Haill, T.A., primary, Brunner, T.A., additional, Budge, K.G., additional, Campbell, R.B., additional, Desjarlais, N.I., additional, Garasi, C.J., additional, Lawrence, R.J., additional, Lemke, R.W., additional, Mehlhorn, T.A., additional, Robinson, A.C., additional, Cochrane, K., additional, and Oliver, B.V., additional

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