|hsu_talk.pdf||2006-02-20 13:47:12||Scott Hsu|
Spherical Torus with a Plasma Center Column (ST-PCC)
Author: Scott C Hsu
Submitted: 2005-12-23 15:41:03
Co-authors: Xianzhu Tang, Mark Kostora
Los Alamos National Laboratory
Los Alamos, NM 87545
The spherical torus (ST) is a promising magnetic confinement configuration, offering higher maximum plasma beta than conventional tokamaks. However, the low aspect ratio requirement results in severe space-constraint for the material center column, which in a conventional ST reactor must house the inboard toroidal field (TF) coils, the Ohmic solenoid, and shielding against fusion neutrons. We propose a concept exploration project to form a spherical torus (ST) with a plasma center (PCC) column via driven relaxation of a screw pinch plasma. An ST-PCC could in principle overcome many of the weaknesses of a material center column. The PCC used in combination with coaxial helicity injection (CHI) could serve four purposes: (1) ST formation via driven relaxation of a screw pinch plasma, (2) carry the inboard TF coil current, (3) help sustain the ST in steady-state in combination with rf and neutral beams, and (4) eliminate the need for neutron shielding since there is no material center column to suffer radiation damage. Using Taylor-relaxed plasmas as a starting point, this Skunkworks presentation will describe the design space for an ST-PCC in terms of flux amplification, aspect ratio, elongation, and vacuum bias flux. Equilibrium and stability properties of the ST-PCC as well as challenges for an engineering design will be discussed. Finally, we will point out how our proposed project complements the ProtoSphera project in Italy, the only other effort in the world investigating the ST-PCC concept.
This is a Skunkworks submission for oral consideration.