Development Of CECE Diagnostic For Measuring Small-amplitude Electron Temperature Fluctuations On EAST

In the burning plasmas,the fusion product α particles will first heat the electrons and then heat the ions by collision,thus the electron heat transport plays a key role in de-termining the performance of the fusion reactor.The current understanding of electron heat transport is relatively weak,so it is necessary to study the physical mechanism of electron heat transport.The study of electron heat transport relies on the measurement of profiles,fluctuations amplitude and phase for fundamental plasma parameters such as Te,ne,B.The main objective of this master’s dissertation is to use the correlation electron cyclotron emission（CECE）diagnostic to measure the small-amplitude electron temperature fluctuation of the EAST plasma.The work will pave the way for the study of multi-field fluctuations on EAST.The first part of this thesis is the design of an integrated quasi-optical antenna system for the CECE system and a DBS（Doppler backscaterring）system.Based on the Gaussian optics design principles,the required mirror parameters are determined.The beam radius of the CECE diagnosis are around 15.5 mm-18.5 mm,consequently the CECE system is sensitive to the turbulence with poloidal wavenumber of k_θ ≤ 2.02 cm^-1.The influence of the mirror size on the light throughput and the beam pattern was studied by using ZEMAX.Finally the ellipsoidal mirror size was determined to be 100 mm（the size of the projection in the plane perpendicular to the propagation direction）,and this value is 3（2.3）times the beam radius for 108（75）GHz emission.The light throughput of the 108 GHz frequency is 99.5%,and the number is 95.5%for 75 GHz.The beam pattern is close to the prediction of the Gaussian optics（deviation of 1.3%for 108 GHz and 5%for 75 GHz）.The newly designed quasi-optical antenna system was installed on EAST in April 2017,and will be used to collect the plasma emission in 2017 EAST campaign.The second part of this thesis is to build a heterodyne radiometer system to measure the electron cyclotron emission of EAST plasma.The characterization of linearity and frequency response of the system in the laboratory is carried out and the results are fairly well.The new heterodyne radiometer system was commissioned by using the existing quasi-optical system of the conventional electron cyclotron emission diagnostic（ECE）,and the electron temperature fluctuation of the EAST plasma was successfully obtained.The commissioning of the CECE diagnostic using the new quasi-optics with better poloidal resolution is ongoing.