| Spectroscopic diagnostics are widely utilized in high-temperature plasma for providing a wide range of plasma physics parameters,such as identification of impurity species,impurities density,ion temperature,electron temperature,and plasma rotation.For HUST filed-reversed configuration(HFRC)device,the FRC plasma drifting velocity will determine the merged plasma parameters;the rotational mode(n=2)driven by the centrifugal force from plasma rotation may limit its lifetime.Thus,a full-band spectrometer and a Fast response Doppler Spectroscopy(FDS)system are designed to identification of impurity species and to study the rotational velocity,drifting velocity and ion temperature of plasma,so as to support the HFRC device to achieve high-quality FRC plasma..The full-band spectrometer is a 7-module optical fiber spectrometer.In this paper,the optical lens and optical path bracket had been designed,which based on the window distribution in the HFRC device,and realized automatic spectral acquisition.The full-band spectrometer was completed with the spectrum system modulation on J-Text Tokamak,and analyzed the plasma spectral line information in the range of 200-900 nm.Using the collision radiation model,we give a method to measure the electron temperature and density of plasma by using the ratio of spectral line relative intensity,which has been successfully applied to the measurement of plasma parameters generated by plasma gun.A Fast response Doppler Spectroscopy(FDS)system with high throughput,high resolution is under development for studying the drift velocity,rotation velocity,and ion temperature on the HUST field-reversed configuration(HFRC)device.The system has been designed to observe the line shape of oxygen V(O V)ion emission at 278.1 nm(1s22s3p→1s22s3s).A 670 mm focal length large aperature Czerny-Turner monochromator with a 3600g/ mm grating is applied to achieve dispersion.To match the channel size of the multi-anode photomultiplier tube(PMT)detector with the spectral dispersion,a 1-D magnification optics combined with a cylindrical lens assembly and a fiber optic expansion is developed.The spectral resolution is about 0.015 nm and time response reaches 1us.By using a optical fiber bundles to transmit the optical signal to Mc Pherson Model 207 monochromator for linesr dispersion,the linear dispersion reaches 0.33nm/mm and the resolution is 0.015 nm.Through a cylindrical lens assemely to realize 6x magnification in the dispersion direction and without obvious magnification in the perpendicular direction.That makes the linear dispersion reach to 0.055nm/mm.Then the linear dispersion is further amplified by using a fiber optic expansion to achieve a dispersion of 0.011nm/mm per channel(or group).Finally,matched with 32 PMT arrays with a width of 0.8mm.The optical system was ray traced with ZEMAX optical design software,and the performance and parameters of the monochromator system,cylinder lens assembly and FDS system were evaluated.The results showed that the spectrum diagnosis fully met the design parameter requirements.Finally,the photon flux of HFRC plasma O V 278.1nm and the output signal quality of each PMT detector under this flux are analyzed by simulation.The results show that in the time scale of 1us,the output signal strength of the detector reaches the order of 100 m V and the signal-to-noise ratio is about 4.5. |
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