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161 results on '"Hinshelwood, D. D."'

1. Modeling Intense-Electron-Beam Generated Plasmas Using a Rigid-Beam Approximation

Author

Richardson, A. S., Swanekamp, S. B., Isner, N. D., Hinshelwood, D. D., Mosher, D., Adamson, P. E., Rittersdorf, I. M., Petrova, Tz. B., and Watkins, D. J.

Subjects
Physics - Plasma Physics, Physics - Computational Physics
Abstract

A model of an electron-beam-plasma system is introduced to model the electrical breakdown physics of low-pressure nitrogen irradiated by an intense pulsed electron beam. The rapidly rising beam current induces an electric field which drives a return current in the plasma. The rigid-beam model is a reduction of the problem geometry to cylindrical coordinates and simplifications to Maxwell's equations that are driven by a prescribed electron beam current density. The model is convenient for comparing various reductions of the plasma dynamics and plasma chemistry while maintaining a good approximation to the overall magnitude of the beam-created electric field. The usefulness of this model is demonstrated by coupling the rigid-beam model to a fluid plasma model and a simplified nitrogen plasma chemistry. The dynamics of this coupled system are computed for a range of background gas pressures, and the results are compared with experimental measurements. At pressures 1 Torr and above, the simulated line-integrated electron densities are within a factor of two of measurements, and show the same trend with pressure as observed in experiment., Comment: Accepted for publication in Physics of Plasmas

Published
2021
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8. Transmission-line-circuit model of an 85-TW, 25-MA pulsed-power accelerator

Author

Hutsel, B. T., primary, Corcoran, P. A., additional, Cuneo, M. E., additional, Gomez, M. R., additional, Hess, M. H., additional, Hinshelwood, D. D., additional, Jennings, C. A., additional, Laity, G. R., additional, Lamppa, D. C., additional, McBride, R. D., additional, Moore, J. K., additional, Myers, A., additional, Rose, D. V., additional, Slutz, S. A., additional, Stygar, W. A., additional, Waisman, E. M., additional, Welch, D. R., additional, and Whitney, B. A., additional

Published
2018
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9. Optimizing the Ar–Xe infrared laser on the Naval Research Laboratory’s Electra generator.

Author

Apruzese, J. P., Giuliani, J. L., Wolford, M. F., Sethian, J. D., Petrov, G. M., Hinshelwood, D. D., Myers, M. C., Dasgupta, A., Hegeler, F., and Petrova, Ts.

Subjects
INFRARED technology, LASERS, INFRARED radiation, ARGON, XENON, INFRARED equipment, NAVAL research
Abstract

The Ar–Xe infrared laser has been investigated in several series of experiments carried out on the Naval Research Laboratory’s Electra generator. Our primary goals were to optimize the efficiency of the laser (within Electra’s capabilities) and to gain understanding of the main physical processes underlying the laser’s output as a function of controllable parameters such as Xe fraction, power deposition, and gas pressure. We find that the intrinsic efficiency maximizes at ∼3% at a total pressure of 2.5 atm, Xe fraction of 1%, and electron beam power deposition density of 50–100 kW cm-3. We deployed an interferometer to measure the electron density during lasing; the ionization fractions of 10-5–10-4 that it detected well exceed previous theoretical estimates. Some trends in the data as a function of beam power and xenon fraction are not fully understood. The as-yet incomplete picture of Ar–Xe laser physics is likely traceable in large part to significant uncertainties still present in many important rates influencing the atomic and molecular kinetics. [ABSTRACT FROM AUTHOR]

Published
2008
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13. Implosions of NaF plasmas for photopumping a Na-Ne x-ray laser.

Author

Young, F. C., Hinshelwood, D. D., Apruzese, J. P., Deeney, C., Nash, T., and Prasad, R. R.

Subjects
*RADIATION, *PLASMA gases
Abstract

Presents a study that reported measurements of 11 Å radiation powers exceeding 100 GW in experiments where the radiated power is increased by increasing the current driving the implosion. Modifications made to the NaF plasma discharge source; Analysis of the implosions; Average temperature and density of the imploded plasma deduced from the measurements.

Published
1991
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14. Sodium-fluoride discharge for fast Z-pinch experiments.

Author

Welch, B. L., Young, F. C., Commisso, R. J., Hinshelwood, D. D., Mosher, D., and Weber, B. V.

Subjects
PLASMA gases, SODIUM fluoride
Abstract

Presents a study that developed a capillary-discharge plasma source to produce a sodium fluoride-bearing plasma for fast Ζ-pinch implosion experiments. Description of the capillary source; Analysis of the electrical measurements; Determination of the net ion-current density of the plasma using Faraday cups.

Published
1989
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21. Proof of Principle for Active Detection of Fissionable Material Using Intense, Pulsed-Bremsstrahlung-Induced Photofission

Author

NAVAL RESEARCH LAB WASHINGTON DC PLASMA PHYSICS DIV, Commisso, R J, Schumer, J W, Allen, R J, Hinshelwood, D D, Jackson, S L, Murphy, D P, Swanekamp, S B, Weber, B V, Zier, J C, Phlips, B F, Hutcheson, A L, Johnson, W N, Mitchell, L J, Wulf, E A, Woolf, R S, Apruzese, J P, Cooperstein, G, Mosher, D, Hunt, A W, Larsen, Z M, NAVAL RESEARCH LAB WASHINGTON DC PLASMA PHYSICS DIV, Commisso, R J, Schumer, J W, Allen, R J, Hinshelwood, D D, Jackson, S L, Murphy, D P, Swanekamp, S B, Weber, B V, Zier, J C, Phlips, B F, Hutcheson, A L, Johnson, W N, Mitchell, L J, Wulf, E A, Woolf, R S, Apruzese, J P, Cooperstein, G, Mosher, D, Hunt, A W, and Larsen, Z M

Abstract

Photons of the appropriate energy can induce photofission in fissile material. We are investigating the applicability of this mechanism, using photons from bremsstrahlung, for long-range ( 100 m) detection of fissile material using high-power ( 1 TW), pulsed technology so called intense, pulsed active detection. In this report, we describe the results of laboratory, proof-of-principle experiments, supported by computations and analyses, in which a single pulse of 8-MeV endpoint bremsstrahlung from the Naval Research Laboratory Mercury pulsed-power generator (200-kA peak current, 50-ns pulse width) induces photofission in depleted uranium. Fission products are measured using He-3 proportional counters, and plastic (BC408), sodium-iodide (NaI:Tl), and bismuth-germinate-oxide scintillators. Prompt neutrons, delayed neutrons, and delayed gamma-rays from the induced photofission are measured unambiguously. Delayed neutron and gamma-ray measurements are also carried out with various thicknesses of low- and high-atomic-number materials attenuating the bremsstrahlung and fission signatures. Results of simulations and analyses carried out in support of the experiments are in agreement with the measurements. In addition, we demonstrate that relatively simple variations of the diode geometry can increase the efficiency of inducing fissions three-fold over the original geometry. These geometry changes cause the electron beam to be more normally incident onto the tantalum converter and thereby increase the forward-directed bremsstrahlung intensity without changing the driving, electrical power pulse. The results of this work and future directions for this research are presented in this report., The original document contains color images. Sponsored in part by Office of Naval Research. Prepared in collaboration with Naval Research Laboratory, Space Sciences Division, Washington, DC, Engility, Inc., Chantilly, VA, and Idaho State University, Idaho Falls, ID.

Published
2014

22. High-power, photofission-inducing bremsstrahlung source for intense pulsed active detection of fissile material

Author

Zier, J. C., primary, Mosher, D., additional, Allen, R. J., additional, Commisso, R. J., additional, Cooperstein, G., additional, Hinshelwood, D. D., additional, Jackson, S. L., additional, Murphy, D. P., additional, Ottinger, P. F., additional, Richardson, A. S., additional, Schumer, J. W., additional, Swanekamp, S. B., additional, and Weber, B. V., additional

Published
2014
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25. Transmission Line and Electromagnetic Models of the Mykonos-2 Accelerator

Author

NAVAL RESEARCH LAB MONTEREY CA, Madrid, E A, Miller, C L, Rose, D V, Welch, D R, Clark, R E, Mostrom, C B, Stygar, W A, Savage, M E, Hinshelwood, D D, LeChien, K R, NAVAL RESEARCH LAB MONTEREY CA, Madrid, E A, Miller, C L, Rose, D V, Welch, D R, Clark, R E, Mostrom, C B, Stygar, W A, Savage, M E, Hinshelwood, D D, and LeChien, K R

Abstract

Mykonos is a linear transformer driver (LTD) pulsed power accelerator currently undergoing testing at Sandia National Laboratories. Mykonos-2, the initial configuration, includes two 1-MA, 200-kV LTD cavities driving a water-filled transmission line terminated by a resistive load. Transmission line and 3D electromagnetic (EM) simulation models of high-current LTD cavities have been developed [D.V. Rose et al. Phys. Rev. ST Accel. Beams 13, 90401 (2010)]. These models have been used to develop an equivalent two-cavity transmission line model of Mykonos-2 using the BERTHA transmission line code. The model explicitly includes 40 bricks per cavity and detailed representations of the water-filled transmission line and resistive load. (A brick consists of two capacitors and a switch connected in series.) This model is compared to 3D EM simulations of the entire accelerator including detailed representations of the individual capacitors and switches in each cavity. Good agreement is obtained between the two simulation models and both models are in good agreement with preliminary data from Mykonos-2., See also ADM002371. 2013 IEEE Pulsed Power Conference, Digest of Technical Papers 1976-2013, and Abstracts of the 2013 IEEE International Conference on Plasma Science. IEEE International Pulsed Power Conference (19th). Held in San Francisco, CA on 16-21 June 2013., The original document contains color images.

Published
2013

26. Conversion of Mercury (a 2-TW Inductive Voltage Adder) to Positive Polarity

Author

NAVAL RESEARCH LAB WASHINGTON DC PLASMA PHYSICS DIV, Allen, R J, Berry, C L, Commisso, R J, Featherstone, E, Fisher, R, Cooperstein, G, Hinshelwood, D D, Jackson, S L, Miller, A T, Ottinger, P F, NAVAL RESEARCH LAB WASHINGTON DC PLASMA PHYSICS DIV, Allen, R J, Berry, C L, Commisso, R J, Featherstone, E, Fisher, R, Cooperstein, G, Hinshelwood, D D, Jackson, S L, Miller, A T, and Ottinger, P F

Abstract

After 616 shots in a negative polarity configuration, Mercury, a 6-MV and 300-kA inductive voltage adder (IVA), has been converted to positive polarity in order to extract ion beams. Conversion to positive polarity was achieved by rotating all six of the adder cells by 180 . In principle, we could have chosen to instead insert the center conductor from the other end of the adder to change polarity, but rotating the cells minimized the time required to make the transition. Although most of the same pieces were used, the center conductor had to be reconfigured in order to align the transition pieces with the cell feed gaps. Because the electron flow was anticipated to be very different in positive polarity, a result of emission from surfaces of different potential, a simple blade diode was fielded for the initial shots to gain a better understanding of operation in positive polarity. The blade diode consisted of the same cathode used as a dummy load in the first negative polarity shots on Mercury, but with a different carbon anode that just covered the end of the center conductor. After a few short circuit and initializing shots, a series of shots were taken where only the blade diode AK gap was varied in order to characterize self-limited and load-limited operation and to compare measurements with theory and simulation., See also ADM002371. 2013 IEEE Pulsed Power Conference, Digest of Technical Papers 1976-2013, and Abstracts of the 2013 IEEE International Conference on Plasma Science. IEEE International Pulsed Power Conference (19th). Held in San Francisco, CA on 16-21 June 2013., The original document contains color images.

Published
2009

29. Electron-beam optimization for bremsstrahlung-induced photofission

Author

Zier, J. C., primary, Mosher, D., additional, Jackson, S. L., additional, Richardson, A. S., additional, Commisso, R. J., additional, Cooperstein, G., additional, Hinshelwood, D. D., additional, Murphy, D. P., additional, Ottinger, P. F., additional, Schumer, J. W., additional, and Swanekamp, S. B., additional

Published
2013
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30. Quick turnaround positive polarity options for mercury

Author

Allen, R. J., primary, Commisso, R. J., additional, Cooperstein, G., additional, Hinshelwood, D. D., additional, Jackson, S. L., additional, Ottinger, P. F., additional, Schumer, J. W., additional, Swanekamp, S. B., additional, and Zier, J. C., additional

Published
2013
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32. Reflex Triode X-Ray Source Research on Gamble

Author

NAVAL RESEARCH LAB WASHINGTON DC PLASMA PHYSICS DIV, Weber, B V, Commisso, R J, Cooperstein, G, Hinshelwood, D D, Mosher, D, Murphy, D P, Stephanakis, S J, Swanekamp, S B, NAVAL RESEARCH LAB WASHINGTON DC PLASMA PHYSICS DIV, Weber, B V, Commisso, R J, Cooperstein, G, Hinshelwood, D D, Mosher, D, Murphy, D P, Stephanakis, S J, and Swanekamp, S B

Abstract

Reflex diode and triode x-ray sources are investigated on Gamble II (2 MV, 2 Omega, 100 ns) to understand the coupling of high-power (TW), MeV-electron beams to thin converters in order to optimize emission of sub-100- keV x-rays. Thin converters reduce self-absorption of low-energy x-rays, but the beam electrons must pass many times through the converter for efficient x-ray production. The triode configuration was found to be superior to diode configurations for this purpose. A large range of converter thicknesses were tested, from 2.5-micrometer gold to 250-micrometer tantalum. The highest dose was obtained from 25-micrometer tantalum, although the spectrum became softer for thinner converters. Computer modeling is in very good agreement with the experimental data, and indicates that electron loss to large radius determines the optimum converter thickness. The coupling efficiency for thinner converters could be improved by decreasing the triode impedance, a motivation for developing similar diodes on higher-current generators., See also ADM002371. 2013 IEEE Pulsed Power Conference, Digest of Technical Papers 1976-2013, and Abstracts of the 2013 IEEE International Conference on Plasma Science. IEEE International Pulsed Power Conference (19th). Held in San Francisco, CA on 16-21 June 2013., The original document contains color images.

Published
2007

35. Modelling of the 7Li(p,n)7Be neutron yield from mercury using GEANT-4 and LSP

Author

Rubery, M., primary, Threadgold, J., additional, O'Malley, J., additional, Clemett, C., additional, Ellis, M., additional, Martin, P. N., additional, Thandi, A., additional, Zier, J. C., additional, Jackson, S. L., additional, Hinshelwood, D. D., additional, Mosher, D., additional, Allen, R. J., additional, Apruzese, J. P., additional, Commisso, R. J., additional, Murphy, D. P., additional, Phipps, D. G., additional, Schumer, J. W., additional, Weber, B. V., additional, Young, F. C., additional, Hutchinson, A., additional, Mitchell, L., additional, Phlips, B., additional, Wulf, E., additional, and Woolf, R., additional

Published
2012
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36. Prompt sub-MeV neutron production from the 7Li(p,n)7Be reaction on mercury

Author

Moshera, D., primary, Apruzesea, J. P., additional, Commisso, R. J., additional, Hinshelwood, D. D., additional, Jackson, S. L., additional, Schumer, J. W., additional, Young, F. C., additional, Zier, J. C., additional, O'Malley, J., additional, Clemett, C., additional, Ellis, M., additional, Martin, P. N., additional, Thandi, A., additional, Threadgold, J. R., additional, Hutcheson, L., additional, Mitchell, L. J., additional, Phlips, B. F., additional, Woolf, R. S., additional, and Wulf, E. A., additional

Published
2012
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41. Ion diode performance on a positive polarity inductive voltage adder with layered magnetically insulated transmission line flow

Author

Hinshelwood, D. D., primary, Ottinger, P. F., additional, Schumer, J. W., additional, Allen, R. J., additional, Apruzese, J. P., additional, Commisso, R. J., additional, Cooperstein, G., additional, Jackson, S. L., additional, Murphy, D. P., additional, Phipps, D., additional, Swanekamp, S. B., additional, Weber, B. V., additional, and Young, F. C., additional

Published
2011
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42. Detectors for intense, pulsed active detection

Author

Jackson, S L, primary, Allen, R J, additional, Apruzese, J P, additional, Commisso, R J, additional, Hinshelwood, D D, additional, Mosher, D, additional, Murphy, D P, additional, Ottinger, P F, additional, Schumer, J W, additional, Swanekamp, S B, additional, Young, F C, additional, Cooperstein, G, additional, Hunt, A W, additional, Seipel, H A, additional, and Gagliardi, M A, additional

Published
2010
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43. 3D electromagnetic and transmissionline models OF A 1-MA linear transformer driver cavity for high-current z pinch accelerators

Author

Miller, C. L., primary, Rose, D. V., additional, Welch, D. R., additional, Madrid, E. A., additional, Clark, R. E., additional, Mostrom, C. B., additional, Stygar, W. A., additional, LeChien, K. R., additional, Mazarakis, M. A., additional, Porter, J. L., additional, Woodworth, J. R., additional, Kim, A. A., additional, and Hinshelwood, D. D., additional

Published
2010
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44. Development of an intense, pulsed source of combined characteristic-gamma-rays and neutrons to induce fission

Author

Commisso, R. J., primary, Schumer, J. W., additional, Apruzese, J. P., additional, Allen, R. J., additional, Cooperstein, G., additional, Hinshelwood, D. D., additional, Jackson, S. L., additional, Mosher, D., additional, Murphy, D. P., additional, Ottinger, P. F., additional, Phipps, D. G., additional, Swanekamp, S. B., additional, Weber, B. V, additional, Young, F. C., additional, Hunt, A., additional, Gagliardi, M., additional, and Seipel, H., additional

Published
2010
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47. Conversion of Mercury (a 2-TW inductive voltage adder) to positive polarity

Author

Allen, R. J., primary, Berry, C. L., additional, Commisso, R. J., additional, Featherstone, E., additional, Fisher, R., additional, Cooperstein, G., additional, Hinshelwood, D. D., additional, Jackson, S. L., additional, Miller, A. T., additional, Ottinger, P. F., additional, Phipps, D. G., additional, and Schumer, J. W., additional

Published
2009
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49. Reflex triode x-ray source research on Gamble II

Author

Weber, B. V., primary, Commisso, R. J., additional, Cooperstein, G., additional, Hinshelwood, D. D., additional, Mosher, D., additional, Murphy, D. P., additional, Stephanakis, S. J., additional, and Swanekamp, S. B., additional

Published
2007
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50. Development of an Intense Pulsed Characteristic γ-Ray Source for Active Interrogation of Special Nuclear Material

Author

Schumer, J. W., primary, Commisso, R. J., additional, Hinshelwood, D. D., additional, Mosher, D., additional, Murphy, D. P., additional, Ottinger, P. F., additional, Phipps, D. G., additional, Stephanakis, S. J., additional, Weber, B. V., additional, Young, F. C., additional, Cooperstein, G., additional, Blackburn, B. W., additional, Jones, J. L., additional, Johnson, J., additional, and Valles, N. O., additional

Published
2007
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