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26 results on '"Doleans, M."'

4. The Spallation Neutron Source accelerator system design

Author

Henderson, S., Abraham, W., Aleksandrov, A., Allen, C., Alonso, J., Anderson, D., Arenius, D., Arthur, T., Assadi, S., Ayers, J., Bach, P., Badea, V., Battle, R., Beebe-Wang, J., Bergmann, B., Bernardin, J., Bhatia, T., Billen, J., Birke, T., Bjorklund, E., Blaskiewicz, M., Blind, B., Blokland, W., Bookwalter, V., Borovina, D., Bowling, S., Bradley, J., Brantley, C., Brennan, J., Brodowski, J., Brown, S., Brown, R., Bruce, D., Bultman, N., Cameron, P., Campisi, I., Casagrande, F., Catalan-Lasheras, N., Champion, M., Chen, Z., Cheng, D., Cho, Y., Christensen, K., Chu, C., Cleaves, J., Connolly, R., Cote, T., Cousineau, S., Crandall, K., Creel, J., Crofford, M., Cull, P., Cutler, R., Dabney, R., Dalesio, L., Daly, E., Damm, R., Danilov, V., Davino, D., Davis, K., Dawson, C., Day, L., Deibele, C., Delayen, J., DeLong, J., Demello, A., DeVan, W., Digennaro, R., Dixon, K., Dodson, G., Doleans, M., Doolittle, L., Doss, J., Drury, M., Elliot, T., Ellis, S., Error, J., Fazekas, J., Fedotov, A., Feng, P., Fischer, J., Fox, W., Fuja, R., Funk, W., Galambos, J., Ganni, V., Garnett, R., Geng, X., Gentzlinger, R., Giannella, M., Gibson, P., Gillis, R., Gioia, J., Gordon, J., Gough, R., Greer, J., Gregory, W., Gribble, R., Grice, W., Gurd, D., Gurd, P., Guthrie, A., Hahn, H., Hardek, T., Hardekopf, R., Harrison, J., Hatfield, D., He, P., Hechler, M., Heistermann, F., Helus, S., Hiatt, T., Hicks, S., Hill, J., Hoff, L., Hoff, M., Hogan, J., Holding, M., Holik, P., Holmes, J., Holtkamp, N., Hovater, C., Howell, M., Hseuh, H., Huhn, A., Hunter, T., Ilg, T., Jackson, J., Jain, A., Jason, A., Jeon, D., Johnson, G., Jones, A., Joseph, S., Justice, A., Kang, Y., Kasemir, K., Keller, R., Kersevan, R., Kerstiens, D., Kesselman, M., Kim, S., Kneisel, P., Kravchuk, L., Kuneli, T., Kurennoy, S., Kustom, R., Kwon, S., Ladd, P., Lambiase, R., Lee, Y.Y., Leitner, M., Leung, K.-N., Lewis, S., Liaw, C., Lionberger, C., Lo, C.C., Long, C., Ludewig, H., Ludvig, J., Luft, P., Lynch, M., Ma, H., MacGill, R., Macha, K., Madre, B., Mahler, G., Mahoney, K., Maines, J., Mammosser, J., Mann, T., Marneris, I., Marroquin, P., Martineau, R., Matsumoto, K., McCarthy, M., McChesney, C., McGahern, W., McGehee, P., Meng, W., Merz, B., Meyer, R., Jr., Meyer, R., Sr., Miller, B., Mitchell, R., Mize, J., Monroy, M., Munro, J., Murdoch, G., Musson, J., Nath, S., Nelson, R., O׳Hara, J., Olsen, D., Oren, W., Oshatz, D., Owens, T., Pai, C., Papaphilippou, I., Patterson, N., Patterson, J., Pearson, C., Pelaia, T., Pieck, M., Piller, C., Plawski, T., Plum, M., Pogge, J., Power, J., Powers, T., Preble, J., Prokop, M., Pruyn, J., Purcell, D., Rank, J., Raparia, D., Ratti, A., Reass, W., Reece, K., Rees, D., Regan, A., Regis, M., Reijonen, J., Rej, D., Richards, D., Richied, D., Rode, C., Rodriguez, W., Rodriguez, M., Rohlev, A., Rose, C., Roseberry, T., Jr., Rowton, L., Roybal, W., Rust, K., Salazer, G., Sandberg, J., Saunders, J., Schenkel, T., Schneider, W., Schrage, D., Schubert, J., Severino, F., Shafer, R., Shea, T., Shishlo, A., Shoaee, H., Sibley, C., Sims, J., Smee, S., Smith, J., Smith, K., Spitz, R., Staples, J., Stein, P., Stettler, M., Stirbet, M., Stockli, M., Stone, W., Stout, D., Stovall, J., Strelo, W., Strong, H., Sundelin, R., Syversrud, D., Szajbler, M., Takeda, H., Tallerico, P., Tang, J., Tanke, E., Tepikian, S., Thomae, R., Thompson, D., Thomson, D., Thuot, M., Treml, C., Tsoupas, N., Tuozzolo, J., Tuzel, W., Vassioutchenko, A., Virostek, S., Wallig, J., Wanderer, P., Wang, Y., Wang, J.G., Wangler, T., Warren, D., Wei, J., Weiss, D., Welton, R., Weng, J., Weng, W-T., Wezensky, M., White, M., Whitlatch, T., Williams, D., Williams, E., Wilson, K., Wiseman, M., Wood, R., Wright, P., Wu, A., Ybarrolaza, N., Young, K., Young, L., Yourd, R., Zachoszcz, A., Zaltsman, A., Zhang, S., Zhang, W., Zhang, Y., and Zhukov, A.

Published
2014
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5. Plasma ignition and detection for in-situ cleaning of 1.3 GHz 9-cell cavities.

Author

Berrutti, P., Giaccone, B., Martinello, M., Grassellino, A., Khabiboulline, T., Doleans, M., Kim, S., Gonnella, D., Lanza, G., and Ross, M.

Subjects
FIELD emission, GLOW discharges, COHERENCE (Optics), PLASMA accelerators, RADIO frequency
Abstract

Superconducting radio frequency cavities performance preservation is crucial, from vertical test to accelerator operation. Field emission is still one of the performance limiting factors to overcome, and plasma cleaning has been proven successful by the Spallation Neutron Source (SNS), in cleaning field emitters (hydrocarbon contaminants) and increasing the work function of Nb. The cleaning for Linac Coherent Light Source-II will follow the same plasma composition adopted at SNS, which allows in situ processing of cavities installed in cryomodules. A novel method for plasma ignition has been developed at the Fermi National Accelerator Laboratory: a plasma glow discharge is ignited using high order modes to overcome limitations imposed by the fundamental power coupler. The plasma can be easily ignited and tuned in each of the cavity cells using low radio frequency (RF) power, from 100 W to as low as 2 W depending on the gas and pressure. A method for RF plasma detection has been developed: the plasma location is identified within the cavity without the need of cameras. The presented method can be applied to other multicell cavity designs, even for accelerators where the coupling for the fundamental modes at room temperature is very weak. [ABSTRACT FROM AUTHOR]

Published
2019
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9. Experimental evidences for emittance degradation by space charge effect when using a focusing solenoid below an electron cyclotron resonance ion source.

Author

Machicoane, G., Doleans, M., Stetson, J., Wu, X., and Závodszky, P. A.

Subjects
*ION sources, *NUCLEAR physics instruments, *IONS, *SCIENTIFIC apparatus & instruments, *RESEARCH equipment
Abstract

Solenoids are widely used to provide initial focusing of beams extracted from an ion source. However, in the case of an electron cyclotron resonance (ECR) ion source, the extracted beam will usually include different ion species and for each of them a wide distribution of charge states. When such a multicomponent beam is focused by a solenoid, the ions with a Q/A larger than the beam of interest are overfocused and usually go through a waist before reaching the analyzing magnet. If the beam currents obtained for these ions are sufficient, the resulting space charge forces can significantly degrade the emittance of the beam components with a lower Q/A and result for those in a hollow beam. Using a beam viewer and an emittance-measuring device, this paper reports on experimental findings that confirm the existence of such an effect for low charge states of argon. Moreover, by changing the experimental conditions of the ECR plasma in order to modify the charge state distribution of the extracted ion beam, it is shown that the threshold where this space charge effect starts to be significant can be changed. [ABSTRACT FROM AUTHOR]

Published
2008
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10. Design, construction, and first commissioning results of superconducting source for ions at NSCL/MSU.

Author

Závodszky, P. A., Arend, B., Cole, D., DeKamp, J., Doleans, M., Machicoane, G., Marti, F., Miller, P., Moskalik, J., Nurnberger, W., Ottarson, J., Vincent, J., Wu, X., and Zeller, A.

Subjects
ION sources, CYCLOTRON resonance, MICROWAVES, SUPERCONDUCTING magnets, SOLENOIDS
Abstract

A new electron cyclotron resonance ion source (ECRIS) was constructed at the NSCL/MSU to replace the existing SC-ECRIS. This ECRIS operates at 18+14.5 GHz microwave frequencies with a planned upgrade to 24–28 GHz in the second phase of commissioning. A superconducting hexapole coil system produce the radial magnetic field; the axial trapping is produced with six superconducting solenoid coils enclosed in an iron yoke to allow the optimization of the distance between the plasma electrode and the resonant zone in the plasma. We report the details of the design, construction, and initial commissioning results of this new ECRIS. [ABSTRACT FROM AUTHOR]

Published
2008
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14. Status report on the NSCL RF fragment separator.

Author

Doleans, M., Andreev, V., Arend, B., Bazin, D., Reyes, A.B., Fontus, R., Glennon, P., Gorelov, D., Mantica, P., Ottarson, J., Schatz, H., Sherrill, B., Stoker, J., Tarasov, O., Vincent, J., Wagner, J., Wu, X., and Zeller, A.

Published
2007
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19. Ion beam development for the needs of the JYFL nuclear physics programme.

Author

Koivisto, H., Suominen, P., Ropponen, T., Ropponen, J., Koponen, T., Savonen, M., Toivanen, V., Wu, X., Machicoane, G., Stetson, J., Zavodszky, P., Doleans, M., Spädtke, P., Vondrasek, R., and Tarvainen, O.

Subjects
ION sources, CYCLOTRONS, SPUTTERING (Physics), CRYOSTATS, NUCLEAR physics instruments
Abstract

The increased requirements towards the use of higher ion beam intensities motivated us to initiate the project to improve the overall transmission of the K130 cyclotron facility. With the facility the transport efficiency decreases rapidly as a function of total beam intensity extracted from the JYFL ECR ion sources. According to statistics, the total transmission efficiency is of the order of 10% for low beam intensities (Itotal<=0.7 mA) and only about 2% for high beam intensities (Itotal>1.5 mA). Requirements towards the use of new metal ion beams for the nuclear physics experiments have also increased. The miniature oven used for the production of metal ion beams at the JYFL is not able to reach the temperature needed for the requested metal ion beams. In order to fulfill these requirements intensive development work has been performed. An inductively and a resistively heated oven has successfully been developed and both are capable of reaching temperatures of about 2000 °C. In addition, sputtering technique has been tested. GEANT4 simulations have been started in order to better understand the processes involved with the bremsstrahlung, which gives an extra heat load to cryostat in the case of superconducting ECR ion source. Parallel with this work, a new advanced ECR heating simulation program has been developed. In this article we present the latest results of the above-mentioned projects. [ABSTRACT FROM AUTHOR]

Published
2008
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26. The MSU EBIT at NSCL.

Author

Lapierre, A., Bollen, G., Lopez-Urrutia, J. R. Crespo, Doleans, M., Geyer, S., Kester, O., Kittimanapun, K., Portillo, M., and Schwarz, S.

Published
2010
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