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Title: Characterization of Self-Magnetic Pinch (SMP) Radiographic Diode Performance on RITS-6 at Sandia National Laboratories.

Abstract

The goals of an electron beam - driven radiographic source are the focusing of high current at high voltage to a minimal spot size with excellent shot - to - shot reproducibility. The Self - Magnetic Pinch (SMP) diode makes use of such an intense electron beam impinging on a high - atomic weight (tantalum) converter, a counter - streaming ion beam to help minimize the spot size, and operation in a magnetic field - free diode region which further encourages small spot size. Through a series of diode development e xperiments, output voltages up to 12.5 MV and output currents up to 225 kA have been characterized, with resulting spot sizes below %7E few mm. Scaling studies with parameter variation, such as diode aspect ratio and anode - cathode (A - K) gap variation, give s ystematic validation to what has heretofore been noted anecdotally by other research groups. While the lack of an imbedded magnetic field helps minimize the SMP spot size, a secondary result may be the generation of beam instabilities which can terminate t he radiation pulse. There is anecdotal evidence that in - situ DC heating of the diode region can help stabilize the beammore » pinch. Clear experimental evidence exists that DC heating/RF cleaning results in better control over the counter - streaming ion populatio n. Expanded use of spatial dose - rate detection is shown to yield new insights into electron beam dynamics in the SMP diode. An attendant study of the SMP diode as a load for an Inductive Voltage Adder (IVA) driver leads to insights into the behavior of the IVA - SMP diode configuration, viewed as a total system, and yields constraints on the overall impedance behavior of the SMP diode load. ACKNOWLEDGEMENTS The authors acknowledge the technical support of the RITS - 6 facility staff Dan Nielsen, Derek Ziska, Bill Bui, Steve Cordova, Robert Obregon, Frank Wilkins, and Ray Gignac. Darryl Droemer provided key diagnostic support. The authors also gratefully acknowledge the key role of Dr. Bruce Weber of the Naval Research Laboratory in the execution of the ITS - CYLTRAN simulations required to quantify the Radiographers Equation specific to the RITS geometry, and listed in Appendi x 2 as Eq. A2 - 1. Dr. Weber also contributed the plots in Figs. A2 - 28b and A2 - 29b in Appendix 2. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned s ubsidiary of Honeywell International, Inc., for the U.S. Department of Energys National Nuclear Security Administration under contract DE - NA0003525.« 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:
1678823
Report Number(s):
SAND2020-10868
691481
DOE Contract Number:  
AC04-94AL85000
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English

Citation Formats

Renk, Timothy Jerome, Kiefer, Mark L., Oliver, Bryan V., Webb, Timothy Jay, Leckbie, Joshua, Johnston, Mark D., Simpson, Sean, and Mazarakis, Michael G. Characterization of Self-Magnetic Pinch (SMP) Radiographic Diode Performance on RITS-6 at Sandia National Laboratories.. United States: N. p., 2020. Web. doi:10.2172/1678823.
Renk, Timothy Jerome, Kiefer, Mark L., Oliver, Bryan V., Webb, Timothy Jay, Leckbie, Joshua, Johnston, Mark D., Simpson, Sean, & Mazarakis, Michael G. Characterization of Self-Magnetic Pinch (SMP) Radiographic Diode Performance on RITS-6 at Sandia National Laboratories.. United States. https://doi.org/10.2172/1678823
Renk, Timothy Jerome, Kiefer, Mark L., Oliver, Bryan V., Webb, Timothy Jay, Leckbie, Joshua, Johnston, Mark D., Simpson, Sean, and Mazarakis, Michael G. Thu . "Characterization of Self-Magnetic Pinch (SMP) Radiographic Diode Performance on RITS-6 at Sandia National Laboratories.". United States. https://doi.org/10.2172/1678823. https://www.osti.gov/servlets/purl/1678823.
@article{osti_1678823,
title = {Characterization of Self-Magnetic Pinch (SMP) Radiographic Diode Performance on RITS-6 at Sandia National Laboratories.},
author = {Renk, Timothy Jerome and Kiefer, Mark L. and Oliver, Bryan V. and Webb, Timothy Jay and Leckbie, Joshua and Johnston, Mark D. and Simpson, Sean and Mazarakis, Michael G.},
abstractNote = {The goals of an electron beam - driven radiographic source are the focusing of high current at high voltage to a minimal spot size with excellent shot - to - shot reproducibility. The Self - Magnetic Pinch (SMP) diode makes use of such an intense electron beam impinging on a high - atomic weight (tantalum) converter, a counter - streaming ion beam to help minimize the spot size, and operation in a magnetic field - free diode region which further encourages small spot size. Through a series of diode development e xperiments, output voltages up to 12.5 MV and output currents up to 225 kA have been characterized, with resulting spot sizes below %7E few mm. Scaling studies with parameter variation, such as diode aspect ratio and anode - cathode (A - K) gap variation, give s ystematic validation to what has heretofore been noted anecdotally by other research groups. While the lack of an imbedded magnetic field helps minimize the SMP spot size, a secondary result may be the generation of beam instabilities which can terminate t he radiation pulse. There is anecdotal evidence that in - situ DC heating of the diode region can help stabilize the beam pinch. Clear experimental evidence exists that DC heating/RF cleaning results in better control over the counter - streaming ion populatio n. Expanded use of spatial dose - rate detection is shown to yield new insights into electron beam dynamics in the SMP diode. An attendant study of the SMP diode as a load for an Inductive Voltage Adder (IVA) driver leads to insights into the behavior of the IVA - SMP diode configuration, viewed as a total system, and yields constraints on the overall impedance behavior of the SMP diode load. ACKNOWLEDGEMENTS The authors acknowledge the technical support of the RITS - 6 facility staff Dan Nielsen, Derek Ziska, Bill Bui, Steve Cordova, Robert Obregon, Frank Wilkins, and Ray Gignac. Darryl Droemer provided key diagnostic support. The authors also gratefully acknowledge the key role of Dr. Bruce Weber of the Naval Research Laboratory in the execution of the ITS - CYLTRAN simulations required to quantify the Radiographers Equation specific to the RITS geometry, and listed in Appendi x 2 as Eq. A2 - 1. Dr. Weber also contributed the plots in Figs. A2 - 28b and A2 - 29b in Appendix 2. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned s ubsidiary of Honeywell International, Inc., for the U.S. Department of Energys National Nuclear Security Administration under contract DE - NA0003525.},
doi = {10.2172/1678823},
url = {https://www.osti.gov/biblio/1678823}, journal = {},
number = ,
volume = ,
place = {United States},
year = {2020},
month = {10}
}