Spheromak Power and Helicity Balance

Thomassen, K.I.

Lawrence Livermore National Laboratory

关键词: 70 Plasma Physics And Fusion Technology;    Geometry;    Efficiency;    Helicity;    72 Physics Of Elementary Particles And Fields;   

DOI  :  10.2172/793865
RP-ID  :  UCRL-ID-138934
RP-ID  :  W-7405-Eng-48
RP-ID  :  793865

美国|英语

来源: UNT Digital Library

【 摘 要 】

This note addresses the division of gun power and helicity between the open line volume and the closed flux surface volume in a steady state flux core spheromak. Our assumptions are that fine scale turbulence maintains each region close to a Taylor state, {mu}{sub o}J = {lambda}B. The gun region that feeds these two volumes surrounded by a flux conserver is shown topologically below. (The actual geometry is toroidal). Flux and current from the magnetized gun flow on open lines around the entire closed surface containing the spheromak. The gun current flows down the potential gradient, the potential difference between the two ends of each line being the gun voltage. Here, the gun voltage excludes the sheath drops at each end. When these volumes have different values of {lambda} (ratio of {mu}{sub o}B{sup -2}j {center_dot} B in each region) in the open line volume V{sub 1} and the closed spheromak volume V{sub 2} the efficiency of transferring the gun power to the spheromak to sustain the ohmic loss is the {lambda}-ratio of these regions, in the limit V{sub 1} << V{sub 2}. This result follows immediately from helicity balance in that limit. Here we give an accounting of all the gun power, and do not assume a small edge (open line) region.