DING Xuantong YANG Qingwei YAN Longwen LIU Dequan XIAO Zhenggui ZHU Genliang LIU Yi ZHOU Yan PAN Yudong CUI Zhengying LIU Zetian SHI Zhongbing JI Xiaoquan XIAO Weiwen LIU Yong
An analytical algorithm for fast calculation of the Abel inversion for density profilemeasurement in tokamak is developed.Based upon the assumptions that the particle source isnegligibly small in the plasma core region,density profiles can be approximated by an asymmetricalGaussian distribution controlled only by one parameter VoID and VoID is constant along theradial direction,the analytical algorithm is presented and examined against a testing profile.Thevalidity is confirmed by benchmark with the standard Abel inversion method and the theoreticalprofile.The scope of application as well as the error analysis is also discussed in detail.
Three spectroscopic systems have been developed for the study of light impurityparticle transport in the HT-7 tokamak.A visible multi-channel spectroscopic system(VIS)is usedto obtain the brightness distribution of the line emission from ionized light impurities.The profileof Ze_(ff)(r)has been obtained from the visible multi-channel bremsstrahlung measurement(VB).The system with a rotating hexahedral mirror for space-time resolved spectroscopy measurementfrom ultraviolet to visible(UV)can provide the brightness distribution of two different emissionlines of the light impurities simultaneously.The emissivities by these multi-channel measurementscan be obtained by Abel inversion.The measurement was performed in typical OH discharges inthe HT-7 tokamak.The carbon particle transport was analyzed.The feasibility of these diagnosticsystems for the impurity particle transport study is clearly demonstrated.
O-mode Doppler reflectometer has been successfully developed as an important di-agnostic system on HL-2A.It can be used to measure the turbulence propagation in both plasmaedge and confinement zone.The Doppler reflectometer system consists of two fixed frequencyhomodyne receivers:15 GHz(corresponding to cutoff density of 0.3×10^(19)m^(-3))and 33 GHz(cot-responding to cutoff density of 1.35×10^(19)m^(-3)).The Doppler reflectometry principle and theexperimental arrangements on HL-2A are presented.Meanwhile,the experimental Doppler reflec-tometric spectra under different discharge conditions,with and without ECRH,were obtained.Furthermore,the turbulence propagation velocity change and the profile were also observed indifferent discharge conditions.
Edge plasma characteristics were studied by a fast-scanning 4-probe array and aMach/Reynolds stress/Langmuir 10-probe movable array in the boundary region.These probescould measure the edge plasma temperature,density,poloidal electric field,radial electric field,Reynolds stress,poloidal rotation velocities and their profiles,which could be obtained by changingthe radial positions of the probe array shot by shot.The measured results were used to analyseplasma confinement,turbulent fluctuations and correlations.The fixed flush 3-probe arrays weremounted on the 4-divertor neutralization plates at the same toroidal cross-section in the divertorchamber.These probes were used to measure the profiles of the electron temperature,density andfloat potential in the divertor chamber.Edge plasma behaviours in both limiter configuration anddivertor configuration are compared.The decay lengths of the edge temperature and density weremeasured and is emphasized for plasma behaviours of the supersonic molecular beam injectionand lower hybrid current drive.The dependence of the radial gradient of Reynolds stress on thepoloidal flow and the radial gradient of the electric field on turbulent loss are discussed.
