真 長谷川

Quaternion Analysis of Power Supply for Tokamak Plasma Control

Power supply for plasma control has been developed from condenser bank with ignitron for pulse tokamak plasma to PWM inverter with IGBT for steady tokamak plasma. Quaternion, four-dimensional hypercomplex number is good at describing three-dimensional rotation. Utilizing the performance of the quaternion rotation, we analyze three-phase power electronic circuit for the tokamak plasma control of equilibrium and stability. By further introduction of biquaternion concept, we can deal with phasor of each phase of three-phase AC similarly. But, we have to multiply the rotation operator from the left-hand side and from the right-hand side by using the conjugation. We try to verify the merits beyond the multiplication inconvenience from both sides. Not only symmetrical three-phase AC (positive sequence) but also negative sequence and zero sequence can be dealt with. Concerning quaternion power of three-phase AC, we can obtain the similar result as the one in pq theory. Quaternion can divide three-dimensional vector. The capability is utilized to develop matrix converter strategy based not only on Venturini method but also on space vector method in more detail.

Study on Plasma Shape Reproduction of Spherical

Cauchy-Condition Surface (CCS) method is a numerical approach to reproduce plasma shape which has good precision in conventional tokamak. In order to apply it in the plasma shape repro-duction of Compact PWI experimental Device (CPD) which is a new spherical tokamak in Kyushu University, the calculation results of CCS method on CPD is reported in the paper.