Millimeter-Gap Magnetically Insulated Transmission Line Power Flow Experiments

Technical Report · Mon Sep 01 00:00:00 EDT 2014

DOI:https://doi.org/10.2172/1323370· OSTI ID:1323370

Hutsel, Brian Thomas ^[1]; Stoltzfus, Brian S. ^[1]; Fowler, William E. ^[1]; LeChien, Keith R. ^[1]; Mazarakis, Michael G. ^[1]; Moore, James K. ^[1]; Mulville, Thomas D. ^[1]; Savage, Mark E. ^[1]; Stygar, William A. ^[1]; McKenney, John L. ^[1]; Jones, Peter A. ^[1]; MacRunnels, Diego J. ^[1]; Long, Finis W. ^[1]; Porter, John L. ^[1]

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1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

An experiment platform has been designed to study vacuum power flow in magnetically insulated transmission lines (MITLs). The platform was driven by the 400-GW Mykonos-V accelerator. The experiments conducted quantify the current loss in a millimeter-gap MITL with respect to vacuum conditions in the MITL for two different gap distances, 1.0 and 1.3 mm. The current loss for each gap was measured for three different vacuum pump down times. As a ride along experiment, multiple shots were conducted with each set of hardware to determine if there was a conditioning effect to increase current delivery on subsequent shots. The experiment results revealed large differences in performance for the 1.0 and 1.3 mm gaps. The 1.0 mm gap resulted in current loss of 40%-60% of peak current. The 1.3 mm gap resulted in current losses of less than 5% of peak current. Classical MITL models that neglect plasma expansion predict that there should be zero current loss, after magnetic insulation is established, for both of these gaps. The experiments result s indicate that the vacuum pressure or pump down time did not have a significant effect on the measured current loss at vacuum pressures between 1e-4 and 1e-5 Torr. Additionally, there was not repeatable evidence of a conditioning effect that reduced current loss for subsequent full-energy shots on a given set of hardware. It should be noted that the experiments conducted likely did not have large loss contributions due to ion emission from the anode due to the relatively small current densi-ties (25-40 kA/cm) in the MITL that limited the anode temperature rise due to ohmic heating. The results and conclusions from these experiments may have limited applicability to MITLs of high current density (>400 kA/cm) used in the convolute and load region of the Z which experience temperature increases of >400° C and generate ion emission from anode surfaces.

• Research Organization: Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• DOE Contract Number: AC04-94AL85000
• OSTI ID: 1323370
• Report Number(s): SAND2014-17769; 537580
• Country of Publication: United States
• Language: English

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