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Title: Plasma Measurements in High Intensity Electron Beam Diodes

Abstract

Experiments are being performed on the Self-Magnetic Pinch (SMP) electron beam diode on the RITS-6 accelerator at Sandia National Laboratories. This diode produces a tightly focused electron beam (< 3mm diameter) which is incident on a high atomic number bremsstrahlung x-ray converter. Typical diode parameters are 120 kA, 7 MeV, and 70ns current pulse, giving a ~45ns x-ray pulse. Plasmas from contaminants on the electrode surfaces propagate into the A-K vacuum gap, affecting the impedance, x-ray spectrum, and pulse width. These plasmas are measured using diagnostics, which include: spectroscopy, optical imaging, and photon detection; to obtain velocity, density, and temperature information. These parameters are measured both spatially, using multi-fiber arrays, and temporally, using streak cameras and avalanche photodiodes. Plasma densities and temperatures are determined from detailed, time-dependent, collisional-radiative (CT) and radiation transport (RT) models, which include Stark broadening of the hydrogen-alpha transition line and carbon ion line ratios. These results are combined with hybrid PIC/fluid simulations to model the plasma’s overall behavior. Densities of up to 10^19 cm-3 have been measured on the electrode surfaces, decreasing by several orders of magnitude both radially and axially across the vacuum gap. Electrode plasma expansion velocities of up to 10 cm/microsecond correlate wellmore » with the decreasing impedance profile (~0.5 Ohms/ns) observed during the pulse.« less

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1427289
Report Number(s):
SAND-2015-8898J
609820
DOE Contract Number:  
AC04-94AL85000
Resource Type:
Program Document
Country of Publication:
United States
Language:
English
Subject:
electron beam diodes; plasma spectroscopy; pulsed-power; flash x-ray radiography

Citation Formats

Kiefer, Mark L., Patel, Sonal, Bennett, Nichelle, Welch, Dale Robert, Bernshtam, V., Doron, R., and Maron, Yitzhak. Plasma Measurements in High Intensity Electron Beam Diodes. United States: N. p., 2015. Web.
Kiefer, Mark L., Patel, Sonal, Bennett, Nichelle, Welch, Dale Robert, Bernshtam, V., Doron, R., & Maron, Yitzhak. Plasma Measurements in High Intensity Electron Beam Diodes. United States.
Kiefer, Mark L., Patel, Sonal, Bennett, Nichelle, Welch, Dale Robert, Bernshtam, V., Doron, R., and Maron, Yitzhak. Thu . "Plasma Measurements in High Intensity Electron Beam Diodes". United States. https://www.osti.gov/servlets/purl/1427289.
@article{osti_1427289,
title = {Plasma Measurements in High Intensity Electron Beam Diodes},
author = {Kiefer, Mark L. and Patel, Sonal and Bennett, Nichelle and Welch, Dale Robert and Bernshtam, V. and Doron, R. and Maron, Yitzhak},
abstractNote = {Experiments are being performed on the Self-Magnetic Pinch (SMP) electron beam diode on the RITS-6 accelerator at Sandia National Laboratories. This diode produces a tightly focused electron beam (< 3mm diameter) which is incident on a high atomic number bremsstrahlung x-ray converter. Typical diode parameters are 120 kA, 7 MeV, and 70ns current pulse, giving a ~45ns x-ray pulse. Plasmas from contaminants on the electrode surfaces propagate into the A-K vacuum gap, affecting the impedance, x-ray spectrum, and pulse width. These plasmas are measured using diagnostics, which include: spectroscopy, optical imaging, and photon detection; to obtain velocity, density, and temperature information. These parameters are measured both spatially, using multi-fiber arrays, and temporally, using streak cameras and avalanche photodiodes. Plasma densities and temperatures are determined from detailed, time-dependent, collisional-radiative (CT) and radiation transport (RT) models, which include Stark broadening of the hydrogen-alpha transition line and carbon ion line ratios. These results are combined with hybrid PIC/fluid simulations to model the plasma’s overall behavior. Densities of up to 10^19 cm-3 have been measured on the electrode surfaces, decreasing by several orders of magnitude both radially and axially across the vacuum gap. Electrode plasma expansion velocities of up to 10 cm/microsecond correlate well with the decreasing impedance profile (~0.5 Ohms/ns) observed during the pulse.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2015},
month = {10}
}

Program Document:
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