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3. PHYSICS DESIGN FOR NDCX-II, A SHORT-PULSE ION BEAM DRIVER FOR NEAR-TERM WDM AND TARGET PHYSICS STUDIES

Author

Friedman, A., Cohen, R. H., Grote, D. P., Sharp, W. M., Henestroza, E., Jung, J.-Y., Leitner, M., Logan, B. G., and Waldron, W. L.

Abstract

The Heavy Ion Fusion Science Virtual National Laboratory, a collaboration of LBNL, LLNL, and PPPL, is studying Warm Dense Matter (WDM) physics driven by ion beams, and basic target physics for heavy-ion-driven inertial fusion. A low-cost architecture for the next-step facility in this program, NDCX-II, has been enabled by the recent donation of induction cells and associated hardware from the decommissioned Advanced Test Accelerator (ATA) facility at LLNL. This second-generation Neutralized Drift Compression eXperiment represents a significant upgrade from the existing NDCX-I. NDCX-II is to deliver ~;30 nC of ions at ~;3 MeV in about 1 ns into a mm-scale spot on a variety of targets. Applications will include studies of the basic physics of the WDM regime using uniform volumetric ion heating of foils at energies near the Bragg peak of deposition; studies of ion energy coupling into an ablating plasma using beams with ramped kinetic energy (relevant to highly efficient heavy-ion direct drive); studies of space-charge-dominated ion beam dynamics; and studies of beam focusing and pulse compression in neutralizing plasma. We have used a combination of analysis, an interactive one-dimensional kinetic simulation model, and multidimensional Warp-code simulations to develop a physics design for the NDCX-II accelerator section. In this design, the pulse of singly charged Li ions is compressed rapidly using an "energy chirp," that is, by imparting a greater kinetic energy to the latter particles in the beam. This compression brings the pulse duration below 70 ns, at which point the high-voltage blumlein power supplies from ATA are usable. The beam is allowed to stretch spatially as it is further accelerated, and then a final energy chirp is applied, the beam is directed into a neutralizing plasma channel, and finally the accelerated and compressed pulse is focused onto the target. The compression from ~;500 ns to ~;1 ns requires only ~;15 m. We present the novel principles underlying this physics design, and illustrate the beam dynamics using computer-generated videos.

Published
2009

7. Recirculating induction accelerators for heavy-ion fusion

Author

Barnard, J. J., Bangerter, R. O., Deadrick, F., Faltens, A., Friedman, A., Fong, C. G., Godlove, T. F., Grote, D. P., Judd, D. L., Griffith, L. V., Kirbie, H. C., Lee, E. P., Neil, V. K., Newton, M. A., Paul, A. C., Reginato, L. L., Sharp, W. M., Shay, H. D., and Yu, S. S.

Published
1993
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9. Overview of Theory and Modeling in the Heavy Ion Fusion Virtual National Laboratory

Author

Davidson, R. C., primary, Kaganovich, I. D., additional, Lee, W. W., additional, Qin, H., additional, Startsev, E. A., additional, Tzenov, S, additional, Friedman, A, additional, Barnard, J J, additional, Cohen, R H, additional, Grote, D P, additional, Lund, S M, additional, Sharp, W M, additional, Henestroza, E, additional, Lee, E P, additional, Yu, S S, additional, Vay, J -L, additional, Welch, D R, additional, Rose, D V, additional, Olson, C L, additional, and Celata, C. M., additional

Published
2003
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10. Initiation of long, free-standing z discharges by CO[sub 2] laser gas heating.

Author

Niemann, C., Tauschwitz, A., Penache, D., Neff, S., Knobloch, R., Birkner, R., Presura, R., Hoffmann, D. H. H., Yu, S. S., and Sharp, W. M.

Subjects
ION bombardment, COLLISIONS (Nuclear physics)
Abstract

High current discharge channels can neutralize both current and space charge of very intense ion beams. Therefore, they are considered an interesting solution for final focus and beam transport in a heavy ion beam fusion reactor. At the Gesellschaft fuer Schwerionenforschung accelerator facility, 50 cm long, free-standing discharge channels were created in a 60 cm diameter metallic chamber. Discharges with currents of 45 kA in 2 to 25 mbar ammonia (NH[sub 3]) gas are initiated by a CO[sub 2] laser pulse along the channel axis before the capacitor bank is triggered. Resonant absorption of the laser, tuned to the υ[sub 2] vibration of the ammonia molecule, causes strong gas heating. Subsequent expansion and rarefaction of the gas prepare the conditions for a stable discharge to fulfill the requirements for ion beam transport. The influence of an electric prepulse on the high current discharge was investigated. This article describes the laser-gas interaction and the discharge initiation mechanism. We found that channels are magnetohydrodynamic stable up to currents of 45 kA, measured by fast shutter and streak imaging techniques. The rarefaction of the laser heated gas is studied by means of a one-dimensional Lagrangian fluid code (CYCLOPS) and is identified as the dominant initiation mechanism of the discharge. [ABSTRACT FROM AUTHOR]

Published
2002
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11. Terascale simulations for heavy ion inertial fusion energy

Author

Friedman, A, primary, Cohen, R H, additional, Grote, D P, additional, Sharp, W M, additional, Celata, C M, additional, Lee, E P, additional, Vay, J-L, additional, Davidson, R C, additional, Kaganovich, I, additional, Lee, W W, additional, Qin, H, additional, Welch, D R, additional, Haber, I, additional, and Kishek, R A, additional

Published
2000
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12. Gas density measurements with heavy ion beams.

Author

Neff, S., Tauschwitz, A., Niemann, C., Penache, D., Hoffmann, D. H. H., Yu, S. S., and Sharp, W. M.

Subjects
GASES, ION bombardment, FUSION reactors
Abstract

High current discharge channels are a promising option for the final stage of beam transport in a heavy ion fusion reactor. The creation and the properties of the channel are studied at the Gesellschaft fuer Schwerionenforschung accelerator facility. This article discusses a diagnostic technique to determine the neutral gas density channel created by a laser in a neutral gas. The concept is to measure the spreading of an ion beamlet due to collisional scattering with the gas, and thereby deduce the average line-integrated gas density. The results show a density reduction near the axis, which compares favorably with one-dimensional code calculations. [ABSTRACT FROM AUTHOR]

Published
2003
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14. Heavy-ion fusion driver research at Berkeley and Livermore

Author

Seidl, P, Bangerter, R O, Celata, C M, Chupp, W W, De la Rama, F, Eylon, S, Faltens, A, Fessenden, T J, Fawley, W M, Ghiorso, W, Hahn, K D, Henestroza, E, Hipple, R, Judd, D, MacLaren, S, Peters, C, Reginato, L, Vanecek, D L, Stoker, J D, Yu, S, Barnard, J J, Cable, M D, Callahan, D A, Cianciolo, V, Deadrick, F J, Debeling, A, Friedman, A, Grote, D P, Holm, K A, Hopkins, H A, Karpenko, V P, Kirbie, H C, Longinotti, D B, Lund, S M, Nattrass, L A, Nelson, M B, Newton, M A, Sangster, T C, and Sharp, W M

Subjects
Accelerators and Storage Rings
Published
1996

15. Beam dynamics of the Neutralized Drift Compression Experiment-II, a novel pulse-compressing ion accelerator

Author

Friedman, A., primary, Barnard, J. J., additional, Cohen, R. H., additional, Grote, D. P., additional, Lund, S. M., additional, Sharp, W. M., additional, Faltens, A., additional, Henestroza, E., additional, Jung, J.-Y., additional, Kwan, J. W., additional, Lee, E. P., additional, Leitner, M. A., additional, Logan, B. G., additional, Vay, J.-L., additional, Waldron, W. L., additional, Davidson, R. C., additional, Dorf, M., additional, Gilson, E. P., additional, and Kaganovich, I. D., additional

Published
2010
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16. Plans for Warm Dense Matter and IFE Target Experiments on NDCX-II

Author

Waldron, W. L., primary, Barnard, J. J., additional, Bieniosek, F. M., additional, Friedman, A., additional, Henestroza, E., additional, Leitner, M. A., additional, Logan, B. G., additional, Ni, P. A., additional, Roy, P. K., additional, Seidl, P. A., additional, and Sharp, W. M., additional

Published
2009
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22. Results on intense beam focusing and neutralization from the neutralized beam experiment

Author

Roy, P. K., primary, Yu, S. S., additional, Eylon, S., additional, Henestroza, E., additional, Anders, A., additional, Bieniosek, F. M., additional, Greenway, W. G., additional, Logan, B. G., additional, Waldron, W. L., additional, Vanecek, D. L., additional, Welch, D. R., additional, Rose, D. V., additional, Davidson, R. C., additional, Efthimion, P. C., additional, Gilson, E. P., additional, Sefkow, A. B., additional, and Sharp, W. M., additional

Published
2004
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23. An Updated Point Design for Heavy Ion Fusion

Author

Yu, S. S., primary, Meier, W. R., additional, Abbott, R. P., additional, Barnard, J. J., additional, Brown, T., additional, Callahan, D. A., additional, Debonnel, C., additional, Heitzenroeder, P., additional, Latkowski, J. F., additional, Logan, B. G., additional, Pemberton, S. J., additional, Peterson, P. F., additional, Rose, D. V., additional, Sabbi, G-L., additional, Sharp, W. M., additional, and Welch, D. R., additional

Published
2003
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25. Progress in heavy ion fusion research

Author

Celata, C. M., primary, Bieniosek, F. M., additional, Henestroza, E., additional, Kwan, J. W., additional, Lee, E. P., additional, Logan, G., additional, Prost, L., additional, Seidl, P. A., additional, Vay, J-L., additional, Waldron, W. L., additional, Yu, S. S., additional, Barnard, J. J., additional, Callahan, D. A., additional, Cohen, R. H., additional, Friedman, A., additional, Grote, D. P., additional, Lund, S. M., additional, Molvik, A., additional, Sharp, W. M., additional, Westenskow, G., additional, Davidson, Ronald C., additional, Efthimion, Philip, additional, Gilson, Erik, additional, Grisham, L. R., additional, Kaganovich, Igor, additional, Qin, Hong, additional, Startsev, Edward A., additional, Bernal, S., additional, Cui, Y., additional, Feldman, D., additional, Godlove, T. F., additional, Haber, I., additional, Harris, J., additional, Kishek, R. A., additional, Li, H., additional, O’Shea, P. G., additional, Quinn, B., additional, Reiser, M., additional, Valfells, A., additional, Walter, M., additional, Zou, Y., additional, Rose, D. V., additional, and Welch, D. R., additional

Published
2003
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28. US heavy ion beam research for high energy density physics applications and fusion

Author

Davidson, R. C., Logan, B. G., Barnard, J. J., Bieniosek, F. M., Briggs, R. J., Callahan, D. A., Kireeff Covo, M., Celata, C. M., Cohen, R. H., Coleman, J. E., Debonnel, C. S., Grote, D. P., Efthimion, P. C., Eylon, S., Friedman, A., Gilson, E. P., Grisham, L. R., Henestroza, E., Kaganovich, I. D., Kwan, J. W., Lee, E. P., Lee, W. W., Leitner, M., Lund, S. M., Meier, W. R., Molvik, A. W., Olson, C. L., Penn, G. E., Qin, H., Roy, P. K., Rose, D. V., Sefkow, A., Seidl, P. A., Sharp, W. M., Startsev, E. A., Tabak, M., Thoma, C., Vay, J.-L., Waldron, W. L., Wurtele, J. S., Welch, D. R., Westenskow, G. A., Yu, S. S., Davidson, R. C., Logan, B. G., Barnard, J. J., Bieniosek, F. M., Briggs, R. J., Callahan, D. A., Kireeff Covo, M., Celata, C. M., Cohen, R. H., Coleman, J. E., Debonnel, C. S., Grote, D. P., Efthimion, P. C., Eylon, S., Friedman, A., Gilson, E. P., Grisham, L. R., Henestroza, E., Kaganovich, I. D., Kwan, J. W., Lee, E. P., Lee, W. W., Leitner, M., Lund, S. M., Meier, W. R., Molvik, A. W., Olson, C. L., Penn, G. E., Qin, H., Roy, P. K., Rose, D. V., Sefkow, A., Seidl, P. A., Sharp, W. M., Startsev, E. A., Tabak, M., Thoma, C., Vay, J.-L., Waldron, W. L., Wurtele, J. S., Welch, D. R., Westenskow, G. A., and Yu, S. S.

Abstract

Key scientific results from recent experiments, modeling tools, and heavy ion accelerator research are summarized that explore ways to investigate the properties of high energy density matter in heavy-ion-driven targets, in particular, strongly-coupled plasmas at 0.01 to 0.1 times solid density for studies of warm dense matter, which is a frontier area in high energy density physics. Pursuit of these near-term objectives has resulted in many innovations that will ultimately benefit heavy ion inertial fusion energy. These include: neutralized ion beam compression and focusing, which hold the promise of greatly improving the stage between the accelerator and the target chamber in a fusion power plant; and the Pulse Line Ion Accelerator (PLIA), which may lead to compact, low-cost modular linac drivers.

Published
2006
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31. Adiabatic focusing and channel transport for heavy ion fusion

Author

Tauschwitz, A., primary, Yu, S. S., additional, Bangerter, R. O., additional, Barnard, J. J., additional, Eylon, S., additional, Fessenden, T. J., additional, Hoffmann, D. H. H., additional, Kwan, J., additional, Leemans, W., additional, de Magistris, M., additional, Peters, C., additional, Reginato, L., additional, and Sharp, W. M., additional

Published
1997
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32. Heavy ion fusion experiments at LLNL

Author

Barnard, J. J., primary, Cable, M. D., additional, Callahan, D. A., additional, Deadrick, F. J., additional, Eylon, S., additional, Fessenden, T. J., additional, Friedman, A., additional, Grote, D. P., additional, Holm, K. A., additional, Hopkins, H. A., additional, Judd, D. L., additional, Hanks, R. L., additional, Hawkins, S. A., additional, Kirbie, H. C., additional, Logan, B. G., additional, Lund, S. M., additional, Nattrass, L. A., additional, Longinotti, D., additional, Nelson, M. B., additional, Newton, M. A., additional, Ollis, C. W., additional, Sangster, T. C., additional, and Sharp, W. M., additional

Published
1996
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35. Recirculating induction accelerators as drivers for heavy ion fusion*

Author

Barnard, J. J., primary, Deadrick, F., additional, Friedman, A., additional, Grote, D. P., additional, Griffith, L. V., additional, Kirbie, H. C., additional, Neil, V. K., additional, Newton, M. A., additional, Paul, A. C., additional, Sharp, W. M., additional, Shay, H. D., additional, Bangerter, R. O., additional, Faltens, A., additional, Fong, C. G., additional, Judd, D. L., additional, Lee, E. P., additional, Reginato, L. L., additional, Yu, S. S., additional, and Godlove, T. F., additional

Published
1993
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37. Steering algorithms for a heavy-ion recirculating accelerator.

Author

Sharp, W. M., Barnard, J. J., and Yu, S. S.

Abstract

For inertial-fusion applications, the beam in proposed recirculating heavy-ion accelerators must complete fifty to one hundred laps around lattices that are between two and four killmeters in circumference. Frequent monitoring and correction of the beam-centroid position is essential to avoid unrealistic tolerances on dipole strengths and quadrupole alignment, the beam centroid. Analytic and numerical estimates are made of the beam-centroid displacement due algorithms for both time-dependent and time-independent beam steering are presented. An envelope-code simulation is used to demonstrate their effectiveness. [ABSTRACT FROM PUBLISHER]

Published
1992

41. Operational Windows for Dry-Wall and Wetted-Wall IFE Chambers

Author

Najmabadi, F., Raffray, A. R., Abdel-Khalik, S. I., Bromberg, L., El-Guebaly, L. A., Goodin, D., Haynes, D., Latkowski, J., Meier, W., Moore, R., Neff, S., Olson, C. L., Perkins, J., Petti, D., Petzoldt, R., Rose, D. V., Sharp, W. M., Sharpe, P., Tillack, M. S., Waganer, L., Welch, D.R., Yoda, M., Yu, S. S., and Zaghloul, M.

Abstract

AbstractThe ARIES-IFE study was an integrated study of inertial fusion energy (IFE) chambers and chamber interfaces with the driver and target systems. Detailed analysis of various subsystems was performed parametrically to uncover key physics/technology uncertainties and to identify constraints imposed by each subsystem. In this paper, these constraints (e.g., target injection and tracking, thermal response of the first wall, and driver propagation and focusing) were combined to understand the trade-offs, to develop operational windows for chamber concepts, and to identify high-leverage research and development directions for IFE research. Some conclusions drawn in this paper are (a) the detailed characterization of the target yield and spectrum has a major impact on the chamber; (b) it is prudent to use a thin armor instead of a monolithic first wall for dry-wall concepts; (c) for dry-wall concepts with direct-drive targets, the most stringent constraint is imposed by target survival during the injection process; (d) for relatively low yield targets (<250 MJ), an operational window with no buffer gas may exist; (e) for dry-wall concepts with indirect-drive targets, a high buffer gas pressure would be necessary that may preclude propagation of the laser driver and require assisted pinch transport for the heavy-ion driver; and (f) generation and transport of aerosols in the chamber is the key feasibility issue for wetted-wall concepts.

Published
2004
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42. Impact of Beam Transport Method on Chamber and Driver Design for Heavy Ion Inertial Fusion Energy

Author

Rose, D. V., Welch, D. R., Olson, C. L., Yu, S. S., Neff, S., and Sharp, W. M.

Abstract

AbstractIn heavy ion inertial fusion energy systems, intense beams of ions must be transported from the exit of the final focus magnet system through the target chamber to hit millimeter spot sizes on the target. In this paper, three different modes of beam propagation are examined: neutralized ballistic transport, assisted pinched transport, and self-pinched transport. The status of the authors’ understanding of these three modes is summarized, and the constraints imposed by beam propagation upon the chamber environment, as well as their compatibility with various chamber and target concepts, are considered. It is concluded that on the basis of the present understanding, there is a reasonable range of parameter space where beams can propagate in thick-liquid-wall, wetted-wall, and dry-wall chambers.

Published
2004
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47. Ruminal VFA Production with Steers Fed Whole or Ground Corn Grain

Author

Sharp, W. M., Johnson, R. R., and Owens, F. N.

Abstract

Ruminal production and interchange rates of volatile fatty acids (VFA) were measured for steers fed corn grain in the whole or ground form. Liquid turnover rate was 29% greater (P<.10) with steers fed the corn in the whole form. On a molar basis (mol/100 mol), ruminal concentrations of propionate were lower while those of butyrate, 3-methyl butyrate, valerate and caproate were greater with whole than with ground corn diets. Acid production differences followed similar trends with de novo production of butyrate being seven times greater and irreversible butyrate loss three times greater with whole than with ground corn diets. Conversion of acetate to butyrate was about 70% greater with whole than with ground corn diets. This conversion far exceeded other VFA exchange rates. Outflow of VFA to the omasum was calculated to equal 20, 25 and 12% of the irreversible loss of acetate, propionate and butyrate, respectively. Ruminal output of energy as VFA from the rumen equaled 60 and 43% of consumed energy with the whole and ground grain diets, respectively. Production rates of VFA were poorly correlated with ruminal concentrations except for butyrate. Less than 10% of the labeled carbon from acetate and butyrate was detected in plasma glucose, but the transfer coefficient from propionate uncorrected for crossover of label was 59%. Gluconeogenesis from propionate alone exceeded literature estimates for basal glucose requirements of nonlactating ruminants.

Published
1982
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48. The Effect of PH on Maximum Bacterial Growth Rate and its Possible Role as a Determinant of Bacterial Competition in the Rumen

Author

Russell, J. B., Sharp, W. M., and Baldwin, R. L.

Abstract

Five rumen bacteria were inoculated into media with pH values ranging from 6.7 to 4.7 to determine effects on maximum growth rate. Streptococcus bovis, Bacteroides ruminicola, and Selenomanas ruminantiumappeared to be more resistant to low pH than either Butyrivibrio fibrisolvensor Megasphaera elsdenii. S. Bovis, B. ruminicola, and S. ruminantiumshowed gradual decreases in maximum growth rate as pH decreased while B. fibrisolvensand M. elsdeniishowed an abrupt transition to no growth.Comparison of maximum growth rates among microbes at various pH's shows that ranking of growth rate between individual species can be pH dependent. The results suggest that pH can be a significant factor determining competition among bacteria in the rumen.

Published
1979
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