Field and Current Amplification in the SSPX Spheromak

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https://www-pub.iaea.org/MTCD/Publications/PDF/csp_019c/html/node68.htm

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http://hdl.handle.net/11603/31479

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UMBC Mechanical Engineering Department

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https://orcid.org/0000-0002-6830-3126

Date

2003

Type of Work

conference papers and proceedings
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Citation of Original Publication

Hill, D. N., et al. “(EX/C1-3) Field and Current Amplification in the SSPX Spheromak.” Presented at 19th International Conference on Fusion Energy 2002, Lyon, France, 14–19 October 2002. https://www-pub.iaea.org/MTCD/Publications/PDF/csp_019c/html/node68.htm.

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This is a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
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Abstract

Recent results from the SSPX spheromak experiment at Livermore show peaked temperature and pressure profiles with low fluctuation levels, core transport coefficients near tokamak L-mode levels, and evidence that the device is operating near a beta limit. These results point to the need for obtaining significant magnetic field amplification. We have added a pulse-forming network to extend the discharge duration and a new set of bias magnetic field coils (which provide a uniquely flexible vacuum field configuration), to explore the physics of magnetic field generation in the spheromak. The bias coils allow low density, high Te ~ 150 eV operation and reduce the threshold current needed to form and maintain the spheromak by about a factor of 2, thereby lowering the fluctuation level. With a flat 3 msec current pulse, we observe steadily increasing field amplification throughout the discharge. We have installed a hyper-resistivity model for helicity transport in the 2d CORSICA code to simulate the observed current amplification. Numerical simulation of the evolution of the magnetic field topology (e.g. internal q-profiles) using the 3d resistive MHD code NIMROD will also be discussed.