Current Drive in Spherical Tokamak Plasmas by the Lower Hybrid Wave

这项研究的目的是证明球形托卡马克所需的等离子体电流可以由高频波驱动。用200 MHz的低杂波成功地驱动了10kA以上的等离子体电流。对比3种天线的实验结果，得到了许多有助于物理理解的重要结果，如球面托卡马克构型的自形成、用波测量表征非线性波动现象、用X射线诊断表征快电子、优化波数谱以及研制新的天线。目前，电流驱动效率受到快速电子损耗的限制，但根据数值模拟，在更高的磁场和更大的等离子体电流下工作，有望大幅提高电流驱动效率。这些结果为提高聚变反应堆的经济竞争力提供了可能。

The purpose of this research is to show that the plasma current needed for spherical tokamaks can be driven by high frequency waves. Plasma currents of over 10kA were driven successfully using the 200MHz lower hybrid wave. Comparing the experimental results obtained using 3 types of antennas, many important results that contribute to the physics understanding, such as self-formation of the spherical tokamak configuration, characterization of nonlinear wave phenomena by wave measurements and of fast electrons by X-ray diagnostics, optimization of wavenumber spectrum, and development of a new antenna, were obtained. Presently, the current drive efficiency is limited by fast electron losses, but according to numerical modeling, a large improvement is expected by operating at higher magnetic field and higher plasma current. These results open up a possibility of improving the economic competitiveness of a fusion reactor.