| As a useful and conventional diagnostic to measure the electron temperature, the soft X-ray pulse height analysis (PHA) system has been installed on many tokamaks. The electron temperature profile with high spatial resolution and appropriate time resolution have been obtained from the soft X-ray PHA in HT-7. It is an important tool to study plasma transport and plasma-wave interactions in LHCD plasma. In this thesis, the theory of measuring electron temperature with the soft X-ray PHA and the system in HT-7 was introduced. The soft X-ray PHA diagnostic measures the line-integrated emission, which the spectrum used to derive the electron temperature is not a local emission. Therefore, the measured spectrum deriving the electron temperature brings some uncertainties. It is discussed in this thesis. It can be obtain that the error with the line-integrated emission is about 10%~20% SX_PHA in HT-7. The error is reversed to density profile factor and fitting energy region e, proportional to temperature profile factor. It is necessary to correct the measured value in discharges with plat density profile, peaked temperature profile. Electron heating via Lower hybrid current drive (LHCD) has been investigated in the HT-7 Superconducting tokamak. Experiments show that the central electron temperature (Te0), the volume averaged electron temperature (), and the peaking factor of the electron temperature (QTe=Te0/) increase with the LHW power. Simultaneous the electron heating efficiency and the electron temperature as the function of the central line-averaged electron density (ne) and the plasma current (Ip) were investigated. The experiment results are in good agreement with the class collision theory.
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