Spectroscopic Diagnostics of Tokamak Plasma Heating by High Power Microwave

1. 在劳伦斯利弗莫尔国家实验室的微波托卡马克实验（MTX）中，我们开发了一种使用激光辅助粒子探针光谱（LAPPS）来测量自由电子激光（FEL）束产生的高功率微波（bbb1gw）的诊断系统。在这个诊断中，我们观察了氦亚稳原子由于斯塔克效应引起的禁止跃迁所引起的荧光，以确定等离子体中的电场强度。在详细讨论了诊断仪器的技术参数后，我们设计了诊断仪器。它由中性氦束流（50keV, 0.2A）、准分子激光激发染料激光激发中性束流和双通道光探测器光谱系统组成。在组装的装置中，我们测量了LAPPS氦束中的三重态亚稳原子密度。为了避免激光产生的杂散光（389 nm, 2^3S*3^3P），我们还观察了级联荧光（706 nm, 3^3S*2^3S），以测量可稳态原子密度。当45 kev氦束流穿过MTX磁场（计算场为96 kV/cm）时，由于斯塔克运动效应，我们通过提高禁跃迁（2^3S*3^3D）来校准FEL电场测量。我们在真空中测量FEL电场的方法与测量vxB电场的方法类似，除了我们必须提取当FEL脉冲到达MTX托卡马克时发生的宽波长带光爆发产生的大背景光。这是首次在托卡马克腔中心测量高功率FEL电场，测量结果（200kv /cm）有助于作为测量等离子体中FEL吸收的标准。由于自由电子激光器发展周期长，时间有限，所以没有对MTX等离子体中的自由电子激光器电场进行测量。总之，我们的联合研究是卓有成效的，我们开发了诊断系统，首次测量了托卡马克等离子体中的电场，并观察到1gw数量级的高功率微波。少

1. We have developed a diagnostic system using laser-aided particle-probe spectroscopy (LAPPS) to measure the high power microwave (>1 GW) generated by a free electron laser (FEL) beam for the ECH study in the Microwave Tokamak Experiment (MTX) at the Lawrence Livermore National Laboratory. In this diagnostics we observe flourescences induced by the forbidden transitions due to the Stark effect from the helium metastable atoms to determine the electric field strength in the plasma.2. We designed the diagnostic apparatus after detailed discussions about the specifications of the apparatus. It consists of a neutral helium beam (50keV, 0.2A), a excimer-laser excited dye laser exciting the neutral beam, and a spectroscopic system with two channels of light detector.3. In the assembled apparatus, we have measured the triplet metastable atom density in the LAPPS helium beam. To avoid stray light due to the laser (389 nm, 2^3S*3^3P), we also observed a cascade flourescence (706 nm, 3^3S*2^3S) … More to measure the matastable atom density.4. We measured the vxB field by raising the forbidden transition (2^3S*3^3D) due to the motional Stark effect when the 45-keV helium beam crossed the MTX magnetic field (the calculated field was 96 kV/cm) to calibrate the FEL electric field measurements.5. We measured the FEL electric-field in vacuum by a similar way as for the vxB field measurement except that we had to extract large background light produced by a wide-wavelength-band light burst that occurred when the FEL pulse reached the MTX tokamak. This is the first time to measure the high power FEL electric-field in the center of tokamak chamber, and the measured result (200 kV/cm) is helpful as a standard to measure the FEL absorption in the plasma.6. Because of time constraints caused by long elapse for the development of FEL, the measurement of the FEL electric-field in the MTX plasma was not made. In conclusion, our Joint Research was fruitful in that we developed the diagnostic system as the first time to measure the electric field in the tokamak plasma and observed the high power microwave of an order of 1 GW. Less