The impact of plasma dynamics on the self-magnetic-pinch diode impedance

The self-magnetic-pinch diode is being developed as an intense electron beam source for pulsed-power-driven x-ray radiography. The basic operation of this diode has long been understood in the context of pinched diodes, including the dynamic effect that the diode impedance decreases during the pulse...

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Bibliographic Details
Published in:Physics of plasmas 2015-03, Vol.22 (3)
Main Authors: Bennett, Nichelle, Crain, M. Dale, Droemer, Darryl W., Gignac, Raymond E., Molina, Isidro, Obregon, Robert, Smith, Chase C., Wilkins, Frank L., Welch, Dale R., Webb, Timothy J., Mazarakis, Michael G., Kiefer, Mark L., Johnston, Mark D., Leckbee, Joshua J., Nielsen, Dan, Romero, Tobias, Simpson, Sean, Ziska, Derek
Format: Article
Language:English
Subjects:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ACCELERATORS
ANODES
CAMERAS
CATHODES
COMPUTERIZED SIMULATION
CRITICAL CURRENT
ELECTRON BEAMS
PINCH DEVICES
PLASMA
PLASMA EXPANSION
PULSES
SANDIA NATIONAL LABORATORIES
TIME DEPENDENCE
TIME RESOLUTION
X-RAY RADIOGRAPHY
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Summary:The self-magnetic-pinch diode is being developed as an intense electron beam source for pulsed-power-driven x-ray radiography. The basic operation of this diode has long been understood in the context of pinched diodes, including the dynamic effect that the diode impedance decreases during the pulse due to electrode plasma formation and expansion. Experiments being conducted at Sandia National Laboratories' RITS-6 accelerator are helping to characterize these plasmas using time-resolved and time-integrated camera systems in the x-ray and visible. These diagnostics are analyzed in conjunction with particle-in-cell simulations of anode plasma formation and evolution. The results confirm the long-standing theory of critical-current operation with the addition of a time-dependent anode-cathode gap length. The results may suggest that anomalous impedance collapse is driven by increased plasma radial drift, leading to larger-than-average ion v{sub r} × B{sub θ} acceleration into the gap.
ISSN:1070-664X
1089-7674