| The diagnostics development is the foundation of the plasma physics experimental study.In these diagnoses electron cyclotron emission(ECE)diagnosis and electron cyclotron emission imaging(ECEI)diagnosis can make use of the millimeter-wave of the electron cyclotron emission from the tokamak plasma to measure the 1-D or 2-D electron temperature distribution and the relative fluctuation.These diagnoses have been widely employed on different magnetic confinement devices because of its great accessibility,high spatial and temporal resolution.The thesis focuses on that the author participated in the design and development of the ECE and ECEI diagnosis on J-TEXT tokamak and carried out the physics experimental study of the plasma transport,confinement and cold pulse experiment based on the ECE diagnosis.This thesis introduced the design of J-TEXT ECE system in the author's early study.A24-channel heterodyne ECE diagnosis system covering 80-125 GHz has been constructed.Its temporal resolution is up to 0.5,and radial spatial resolution is up to 1.25 cm.It could cover more than a half of the plasma region at most toroidal fields.Based on the upward compatibility of the waveguide,the front ECE transmission line made use of W-band waveguide,received the W-band and F-band signals with a single antenna.An ellipsoidal reflector optic has been designed and optimized for ECE systems,to provide the poloidal resolution of 2cm(core)-5cm(edge).The experiments operation of ECE diagnose shown its good and stable performance.It could support the numerous physics experiments with high quality data.The author participated in the design of J-TEXT ECEI system and took charge of the integrated design and the electronics design since 2015 to improve the experiment platform for the study of macroscopic hydromagnetic instability and disruption mechanism.Based on the frequency range calculated from the J-TEXT discharge parameters,and the study aim of hydromagnetic instability and disruption mechanism,the J-TEXT ECEI was confirmed as the scheme of two antenna arrays,each one covering the F-band(90-140 GHz)and W-band(75-110 GHz)respectively,and 2(array)× 8(radial)× 16(poloidal)=256 channels in total.Cooperating with the developed quasi-optics design,this ECEI scheme could not only observe the high field side and the low field side of the same magnetic surface in the plasma separately and simultaneously but also focus on a wide continuous region to meet the different experimental demands.This thesis introduced the design of the antenna arrays and the electronics modules that the author participated in.16 high-pass dichroic plates with different frequencies have been simulated,fabricated and tested to meet the demand of J-TEXT ECEI.The notch filter at 105 GHz has been simulated to block the high power ECRH signal.Their design results met the anticipated goals.To improve the control efficiency of the diagnose,and adapt to the demands of the large devices and future fusion reactors,J-TEXT ECEI electronics modules abandon the scheme of dual in-line package switches in the previous ECEI system,and carried out a brand-new design with the aim of remotely-digital-control.This thesis introduced the choices of each adjustable components with the digital control functions,and the details of their digital control schemes.The connectors on the front panel of electronics modules were also redesigned and optimized to meet the demand of the proliferated control signal channels.Finally,the design of the electronics modules has been completed,and hardware of the ECEI digital control has been achieved.Besides,the new designed ECEI modules extended the measuring ability.The work frequency range of the modules has been extended to 2-12 GHz,much wider than 2-9GHz on the previous ECEI systems.The frequency selection schemes of the modules were also extended to 3 choices instead of 2 choices on the previous ECEI systems.These improvements enhanced the adjusting flexibility of the radial coverage.A lot of testing work surrounding the antenna arrays and the electronics modules was carried out right after the ECEI electronics system was designed,fabricated and assembled.The key issues have been diagnosed,fixed,and the performances of a few components have been optimized during the testing.The debugged and fixed ECEI system has come into the plasma operation in October,2019,got some preliminary measurements,the function of remotelydigital-control worked well and significantly improve the adjusting efficiency.This diagnose basically achieved the anticipated design target.In the meantime of the J-TEXT ECEI development,based on the completed ECE diagnosis on J-TEXT,the author carried out the experimental studies of the measuring of the electron heat diffusivities,plasma confinement transition,and cold pulse experiments.The critical electron density at the fixed discharge parameters was found and compared with the scaling value in the experimental study of the Linear Ohmic Confinement(LOC)/ Saturated Ohmic Confinement(SOC)transition in the pure ohmic discharge.In the cold pulse experiments,different parameters have been calculated from the experiment data,and their variations were compared with each other.Meanwhile,the spectrum analysis of the density fluctuations from the Doppler backward scattering has been performed.It was found that the high-frequency component of the density fluctuation which has a similar wave number with the trapped electron mode turbulence,shown different trends at low and high densities.The experiment analysis believed that the reverse polarity phenomenon on the electron temperature profile could only happen when TEM dominates the electron heat transport,core temperature increasing for edge cooling as TEM stabilization and decreasing for edge heating as TEM destabilization.After the constructions of ECE and ECEI diagnostics,they both worked in the plasma environment and tested by the physics experiments,presented the good spatial measuring ability and high-quality data,and laid a good diagnostics foundation for the physics experiments studies on J-TEXT tokamak. |
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