Conceptual Design Of CFETR Diagnostic System And Study On Diagnostic Port Integration

Chinese Fusion Engineering Test Reactor(CFETR)is a new superconducting tokamak device being designed in China,which aims at bridging gaps between ITER and DEMO.Key objectives of CFETR are the realization of 200MW(Phase I)and 1GW(Phase II)fusion power,the demonstration of tritium self-sufficiency with tritium breeding ratio(TBR)? 1.0 and the exploration of steady state operation(SSO)with duty factor of?0.3-0.5.The diagnostic system,as the device's eyes,is an important way for machine protection,basic control,and improvement of plasma performance.It is important and challenging to design one set of reasonable and robust diagnostic systems for CFETR.This paper mainly includes four important parts.The first part describes the ITER diagnostic system.ITER will integrate nowadays worldwide major scientific and technological achievements on the magnetic confinement nuclear fusion research.Therefore,the design of the CFETR diagnostics can follow the experience obtained in the development of ITER diagnostics.The ITER diagnostic system,which is complex and comprehensive,will provide nearly 100 measurements by utilizing approximately 70 diagnostic systems covering magnetic,laser,microwave,spectral,neutron and fusion products.The second part,which is most important,mainly introduces the current progress of CFETR diagnostics conceptual design.First,the challenge for CFETR diagnostic system is analyzed.The neutron wall load,neutron flux and neutron flunce are calculated.Then,the approach of diagnostics design is givn based on ITER's experience.Later,according to the different requirement in CFETR phase I and II,the schedual of CFETR diagnostics are developed and two diagnostic cases,the ITER-like and towards DEMO have been proposed.Finally,three versions of ITER-like diagnostic case with different functions and redundancy are introduced,and the challenges these diagnostic technologies may have in implication to CFETR are described.The third part focuses on the researches on diagnostic port integration in CFETR,including the challenges during diagnostic port integration,the approach of port integration,the factors for diagnostic distribution.Morever,CFETR device and diagnostic port plug are modeled using CATIA software.Then,three diagnostic systems includes polarization interferometer,H-a spectrum and visible/infrared imaging have been integrated into one diagnostic port plug.The fourth part introduces the design of far-infrared laser vibration compensation interferometer system,which is an advanced research on reactor diagnostic.In the future,the short wave length far-infrared laser interferometer,which is used for electron density measurement,will face the serious problem brought by vibration.Vibration compensation interferometer uses the method of dual wavelength lasers simultaneously,to eliminate the vibration error from the measurement results,which is the necessary technology for the far-infrared laser diagnostic on the future reator device.This section firstly introduces the basic principle of vibration compensation interferometer.Secondly,using two acousto-optic modulators(AOMs)obtained 1 MHZ intermediate frequency signal,and then its stability has been tested.Besides,a nanometer level displacement(of the order of the laser's wavelength)has been clearly measured by a modulation of piezoelectric ceramic unit,proving the system's capability.Finally,the vibration compensation interferometer has been designed based on the environment condition of the EAST tokamak device.