Spectral Line Profile Analysis Using Higher Diffraction Order in Vacuum Ultraviolet Region (original) (raw)
Related papers
2009
Vacuum ultraviolet region, 50nm to 320nm, of tokamak plasma light emission from NOVA-UNICAMP and TCABR has been analyzed using one-meter focal length VUV spectrometer and open MCP/CCD detector. About 86 spectral emissions are detected, where 35 lines are from first diffraction order and others are from second, third and fourth diffraction order. The first order spectral lines are mainly emitted below 150 nm, and the region from 100 nm to 320 nm is useful to observe higher diffraction order lines. Impurity species such as OII, OIII, OIV, OV, OVII, CII, CIII, CIV, are very common lines also present in the larger tokamak plasma. The use of higher diffraction order emissions and the control of pixel distribution over Gaussian profile show to be very important in order to obtain correct ion temperature, due to the narrow Doppler broadening in the VUV region and large instrumental broadening. We conclude that the effect of Gaussian width difference is caused by the wavelength interval covered by each pixel on the Gaussian fit.
VUV spectral line emission measurements in the TCABR tokamak
Brazilian Journal of Physics, 2009
The study of tokamak plasma light emissions in the vacuum ultraviolet (VUV) region is an important subject since many impurity spectral emissions are present in this region. These spectral emissions can be used to determine the plasma ion temperature and density from different species and spatial positions inside plasma according to their temperatures. We have analyzed VUV spectra from 500Å to 3200Å wavelength in the TCABR tokamak plasma including higher diffraction order emissions. There have been identified 37 first diffraction order emissions, resulting in 28 second diffraction order, 24 third diffraction order, and 7 fourth diffraction order lines. The emissions are from impurity species such as OII, OIII, OIV, OV, OVI, OVII, CII, CIII, CIV, NIII, NIV, and NV. All the spectra beyond 1900Å are from higher diffraction order emissions, and possess much better spectral resolution. Each strong and isolated spectral line, as well as its higher diffraction order emissions suitable for plasma diagnostic is identified and discussed. Finally, an example of ion temperature determination using different diffraction order is presented.
Spectroscopic measurements of the ion temperature in front of a tokamak limiter
Journal of Nuclear Materials, 1995
In the beam heated (1.3 MW) plasma of the TEXTOR tokamak, ion temperatures T i between 30 and 120 eV have been measured in front of a test limiter at line averaged electron densities between 4 x 1013 and 1.5 X 1013 cm-3. The Doppler broadened profile of the C VI line A = 529 nm, excited by charge exchange with recycling hydrogen (deuterium) atoms, was used for the T i determination. Errors introduced by finite energy equipartition times between C 6+ and D + ions, by correction for fine structure and the Paschen-Back effect, and by possible blending with an O VI line, are discussed. Profile distortion by superposition of molecular D 2 lines was considerably reduced by observation with a high resolution spectrometer (A/AA > 5 × 104). Estimates of D 2 particle energies and the C 6+ poloidal rotation velocity have been performed.
Impurity Line Emissions in VUV Region of TCABR Tokamak
AIP Conference Proceedings, 2008
Spectral emissions in the vacuum ultraviolet region from 50 nm to 320 nm have been measured on TCABR tokamak using an one meter VUV spectrometer and a MCP coupled to a CCD detector. Among the 98 emissions classified, 37 are from first order diffraction, 29 are from second order, 24 are from third order, 7 from fourth order, and one from fifth order diffraction. Main impurity lines are OII to OVII, CII to CIV, NIII to NV, FVII, besides working gas plasma hydrogen Lyman lines.
The high-resolution absorption spectroscopy branch on the VUV beamline DESIRS at SOLEIL
Journal of Synchrotron Radiation, 2016
A VUV absorption spectroscopy facility designed for ultra-high spectral resolution is in operation as a dedicated branch on the DESIRS beamline at Synchrotron SOLEIL. This branch includes a unique VUV Fourier transform spectrometer (FTS) and a dedicated versatile gas sample chamber. The FTS instrument can cover a large UV–VUV spectral range from 4 to 30 eV, with an ultimate line width of 0.08 cm−1on a large spectral window, ΔE/E= 7%, over which all spectral features can be acquired in a multiplex way. The performance can be considered to be a middle ground between broadband moderate-resolution spectrometers based on gratings and ultra-high-spectral-resolution VUV tunable-laser-based techniques over very narrow spectral windows. The various available gaseous-sample-handling setups, which function over a wide range of pressures and temperatures, and the acquisition methodology are described. A selection of experimental results illustrates the performance and limitations of the FTS-bas...
Calibration of a VUV spectrograph by collisional-radiative modelling of a discharge plasma
Journal of Physics B-atomic Molecular and Optical Physics, 2010
The feasibility of inferring the plasma parameters of a Penning discharge in helium, from the experimentally observed intensities of a number of spectral lines in the visible wavelength region, is explored. The collisional-radiative model of ADAS (atomic data analysis structure) code and database has been used for this analysis. The electron density, electron temperature, ground-state atom and ion densities and also the 2 3S metastable state density are the parameters thus estimated. The results are encouraging. The derived plasma parameters are then used to obtain the intensities of a few lines in the vacuum ultraviolet (VUV) region. This has been compared with the observed VUV spectral lines, recorded simultaneously with the visible lines, using a VUV spectrometer for which intensity calibration was not available, to arrive at calibration factors. It is expected that this approach might provide an alternative to the 'branching ratio' method for calibration in the VUV region once the analysis is improved and the possible re-absorption of certain lines is accounted for.
The Review of scientific instruments, 2014
To optimize the design of ITER vacuum ultraviolet (VUV) spectrometer, a prototype VUV spectrometer was developed. The sensitivity calibration curve of the spectrometer was calculated from the mirror reflectivity, the grating efficiency, and the detector efficiency. The calibration curve was consistent with the calibration points derived in the experiment using the calibrated hollow cathode lamp. For the application of the prototype ITER VUV spectrometer, the prototype spectrometer was installed at KSTAR, and various impurity emission lines could be measured. By analyzing about 100 shots, strong positive correlation between the O VI and the C IV emission intensities could be found.
VUV emission and absorption spectroscopy with a multichannel near normal incidence spectrometer
1998
An experiment for vacuum UV emission and photoabsorption spectroscopy usmg a normal incidence multi-channel spectrometer is described. Two detection configurations were used in the experiments, one a Channel Electron Multiplier Anay with Photo Diode Array readout ( CEMA / PDA), the other a directly illuminated back thmned Charge Coupled Device ( CCD ). Emission spectra of plasmas of a number of low and high Z target matenals were recorded covering the majority of the vacuum UV spectral region ( 35 to 200 nm ). These experiments were designed mainly to study the nature of the emission ( line versus continuum) and it’s dependence on atomic number. The use of two detection configurations allowed for mter comparisons to be made on resolution, efficiency and dynamic range of the two multi-channel detector and spectrometer systems. Experiments were also performed on photoabsorption by helium gas. The spectra thus obtamed were used to help charactense the system’s application to absorption...
VUV spectroscopy in impurity injection experiments at KSTAR using prototype ITER VUV spectrometer
The Review of scientific instruments, 2017
The ITER vacuum ultra-violet (VUV) core survey spectrometer has been designed as a 5-channel spectral system so that the high spectral resolving power of 200-500 could be achieved in the wavelength range of 2.4-160 nm. To verify the design of the ITER VUV core survey spectrometer, a two-channel prototype spectrometer was developed. As a subsequent step of the prototype test, the prototype VUV spectrometer has been operated at KSTAR since the 2012 experimental campaign. From impurity injection experiments in the years 2015 and 2016, strong emission lines, such as Kr xxv 15.8 nm, Kr xxvi 17.9 nm, Ne vii 46.5 nm, Ne vi 40.2 nm, and an array of largely unresolved tungsten lines (14-32 nm) could be measured successfully, showing the typical photon number of 10(13)-10(15) photons/cm(2) s.