Interpretation Of ECE Measurements In LHW-heated Plasmas

Electron temperature with high spatial and temporal resolutions is one of the fun-damental plasma parameters,and it is also essential for active control of neoclassical tearing modes which can degrade the plasma performance seriously.Electron cyclotron emission(ECE)measurement is one of those electron temperature diagnostics.Its char-acter includes:passive measurement,high spatial and temporal resolutions.Lower hybrid wave(LHW)is with highest current drive efficience among the existing tech-niques,and it is necessary for steady state operation.On EAST,LHW system is of very high priority,and most discharges are heated with LHW.In principle,LHW will drive suprathermal electrons and consequently results in a non-Maxwellian electron velocity distribution.This will break the underlying physics of ECE diagnostics,and it is urgent to understand the ECE character in LHW-heated plasmas.In this thesis,the code SPECE is used to simulate the ECE spectra in LHW-heated plasmas on EAST.The results indicate that the radiation with a certain frequency is at-tributed to two emission layers.They are respectively attributed to the thermal electrons and non-thermal electrons.There is still an one-to-one mapping between the major ra?dius and the thermal emission layer position.Whereas,the non-thermal emission layer position is strongly dependent on the character of suprathermal electrons.From the perspective of radiation intensity,the suprathermal electrons have influnce on ECE in a wide frequency range.Even though the intensity is polluted,the information of the lo-calized electron temperature fluctuation driven by macro instabilities can still be derived from ECE measurements as long as the radiation intensity attributed to suprathermal electrons keeps constant.Resutls of sawtooth inversion radius and TM magnetic island location derived from ECE measurements show a good agreement with the restuls from other diagnostics.