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691 results on '"Roy, P.K."'

42. Progress in U.S. Heavy Ion Fusion Research

Author

Logan, B.G., Barnard, J.J., Bieniosek, F.M., Cohen, R.H., Davidson, R.C., Efthimion, P.C., Friedman, A., Gilson, E.P., Grisham, L.R., Grote, D.P., Henestroza, E., Kaganovich, I.D., Kwan, J.W., Lee, E.P., Leitner, M.A., Lidia, S.M., Lund, S.M., More, R.M., Ni, P., Perkins, L.J., Qin, H., Roy, P.K., Seidl, P.A., Sharp, W.M., Startsev, E.A., and Waldron, W.L.

Published
2010

43. Ion beam driven HEDP experiments on NDCX

Author

Bieniosek, F.M., Barnard, J.J., Henestroza, E., Lidia, S., More, R.M., Ni, P.A., Roy, P.K., and Seidl, P.A.

Subjects
Warm Dense Matter, NDCX-I, lithium
Abstract

Intense beams of heavy ions are capable of delivering precise and uniform beam energy deposition, with the capability to heat volumetric samples of any solid-phase target material to high energy density. The WDM conditions are achieved by combined longitudinal and transverse space-charge neutralized drift compression of the ion beam to provide a hot spot on the target with a beam spot size of about 1 mm. Initial experiments use a 0.3 MeV, 30-mA K+ beam from the NDCX-I accelerator to heat foil targets such as Au, Pt, W, Al and Si. The NDCX-1 beam contains a low-intensity uncompressed pulse up to >10 ?s of intensity ~;0.4 MW/cm2, and a high-intensity compressed pulse (FWHM 2-3 ns and fluence ~;4 mJ). WDM experiments heat targets by both the compressed and uncompressed parts of the NDCX-I beam, and explore measurement of temperature, droplet formation and other target parameters. Future plans include target experiments using the NDCX-II accelerator, which is designed to heat targets at the Bragg peak using a 2-3 MeV lithium ion beam.

Published
2010

45. Results of the upgraded Neutralized Drift Compression Experiment

Author

LIDIA, STEVEN M., BIENIOSEK, F.M., GILSON, E.P., ROY, P.K., NI, P., SEIDL, P.A., BOGERT, K. VAN DEN, and WALDRON, W.L.

Abstract

Recent changes to the NDCX beamline offer the promise of higher current compressed bunches, with correspondingly greater fluence delivered to thetarget plane for ion-beam driven warm dense matter experiments. We reportmodeling and commissioning results of the upgraded NDCX beamline that includes a new induction bunching module with approximately twice the volt-seconds and greater tuning flexibility, combined with a longer neutralized drift compression channel.

Published
2009

46. BEAM STEERING, FOCUSING AND COMPRESSION FOR WARM-DENSE MATTER EXPERIMENTS

Author

Lidia, S.M., Anders, A., Cohen, R.H., Coleman, J.E., Dorf, M., Gilson, E.P., Grote, D.P., Jung, J.Y., Leitner, M., Logan, B.G., Roy, P.K., Sefkow, A.B., Seidl, P.A., Waldron, W.L., and Welch, D.R.

Abstract

The Heavy-Ion Fusion Sciences Virtual National Laboratory is pursuing an approach totarget heating experiments in the Warm Dense Matter regime, using space-charge-dominated ion beams that are simultaneously longitudinally bunched andtransversely focused. Axial compression leading to ~;100X current amplification andsimultaneous radial focusing have led to encouraging energy deposition approaching, but still short of, the intensities required for eV-range target heating experiments. We present measurements from the Neutralized Drift Compression Experiment to reach the necessary higher beam intensities, including: (1) axial compression and radial focusing; (2) spatial and temporal distribution of energy deposition at the target plane; and (3) centroid motion of the beam spot through the pulse.

Published
2009

48. A Space-Charge Neutralizing Plasma Channel for an Intense Beam

Author

Barnard, J.J., Seidl, P.A., Roy, P.K., Coleman, J.E., Duersch, J.A., Friedman, A., Gilson, E.P., Jung, J.Y., Leitner, M., Ogata, D., Sefkow, A.B., Waldron, W.L., and Welch, D.R.

Abstract

Ion bunches have been suggested as means to heat matter to the warm dense matter, or strongly coupled plasma regime (Temperature ~; 0.1 to 10 eV). For a K+ beam at 0.4 MeV, ~;1 J/cm2 is required to reach 1 eV in solid Aluminum. Also the pulse duration must be short (

Published
2009

49. A THIN COLUMN OF DENSE PLASMA FOR SPACE-CHARGE NEUTRALIZATION OF INTENSE ION BEAMS

Author

Roy, P.K., Seidl, P. A., Anders, A., Barnard, J.J., Bieniosek, F.M., Friedman, A., Gilson, E. P., Greenway, W., Sefkow, A. B., Jung, J. Y., Lidia, S., Logan, B. G., Waldron, W. L., Welch, D. R., and Leitner, M.

Abstract

Typical ion driven warm dense matter experiment requires a plasma density of 1014/cm3 to meet the challenge of np > nb, where np, and nb are the number densities of plasma and beam, respectively. Plasma electrons neutralize the space charge of an ion beam to allow a small spot of about 1-mm radius. In order to provide np > nb for initial warm, dense matter experiments, four cathodic arc plasma sources (CAPS) have been fabricated, and the aluminum plasma is focused in a focusing solenoid (8T field). A radial plasma probe with 37 collectors was developed to measure the radial plasma profile inside the solenoid. Initial results show that the plasma forms a thin column of diameter ~;7mm along the solenoid axis. The deformation of the magnetic field due to eddy currents, the magnetic mirror effect and plasma condensation are under investigation. Plasma data and ion beam neutralization will be presented.

Published
2009

50. OVERVIEW OF U.S. HEAVY ION FUSION SCIENCE PROGRAM

Author

Henestroza, E., Barnard, J.J., Bieniosek, F.M., Cohen, R.H., Coleman, J.E., Davidson, R.C., Efthimion, P.C., Friedman, A., Gilson, E.P., Grisham, L.R., Grote, D.P., Logan, B.G., Kaganovich, I.D., Lee, E.P., Leitner, M.A., Lund, S.M., Molvik, A.W., Ni, P.A., Perkins, L.J., Qin, H., Roy, P.K., Sefkow, A.B., Seidl, P.A., Startsev, E.A., and Waldron, W.L.

Published
2009

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