Tearing mode structure study using tangential EUV/SXR diagnostic system on HBT-EP tokamak

Measuring and analyzing the intensity of the extreme ultraviolet (EUV) and soft x-ray (SXR) is an effective way to study the internal characteristics of MHD mode structures, including the temperature profiles. We present the progress on the two-color multi-energy EUV/SXR diagnostic system in the HBT-EP tokamak. This system includes a filter wheel with five different groups of dual-filter structure. By using a combination of 100 nm Aluminum and 200 nm Titanium filters with identical plasma views and two AXUV16ELG 16-channel diode arrays, this system can provide temperature profile information versus time by calculating the ratio of the amplitudes of the signals from different filters, calibrated with Thomson scattering system. To improve the frequency response of the amplifiers and advance the ability to study fast rotating modes, we built a new two-stage single-channel amplifier system. It has a bandwidth up to 200 kHz and gains varying from 1 MOhm to 50 MOhm corresponding to different channels of the diode array to optimize the signal amplitudes. The initial results on the dynamics of the m/n=2/1 tearing mode are studied using the system. The line-integrated signals are used to reconstruct the emissivity and temperature profiles of the tangential cross section of the plasma.