Abstract
We reported the relative responsivity calibration of the grazing-incidence flat-field EUV spectrometer between 175 and 435 Å by means of two methods. The first method is implemented by measuring the diffraction efficiency of the grating with synchrotron radiation light source. Considering the transmission efficiency and quantum efficiency of the other optical components in the spectrometer, the total responsivity was then obtained. The second one was carried out by measuring line emissions from C3+, N4+ and O3+ ions at Shanghai high temperature super conductor electron beam ion trap (SH-HtscEBIT). The EUV spectra were also simulated theoretically via a collisional radiative model. In the calculation, the second-order relativistic many-body perturbation theory approach based on the flexible atomic code was used to calculate the energy levels and transition rates; the close-coupling R-matrix approach and relativistic distorted wave method were utilized to calculate the collision strength of electron impact excitation. In comparison with the spectroscopic measurements at EBIT device, the differences between the measured and simulated relative line intensities were obtained. The responsivity calibration for the spectrometer was then achieved by a 3rd degree polynomial function fitting. Our measurement shows that the responsivity between 175 and 435 Å varies by factor of ∼ 46. The two results of calibration demonstrated a consistency within an average deviation of 24%. In addition, an evaluation of our calculations on C iv, N v and O iv line emissions in this wavelength region was given.
Highlights
The extreme ultraviolet (EUV) spectroscopic measurements are meaningful in laboratory plasma researches due to the diagnostic value of plasma conditions.[1,2] At magnetic confinement fusion devices, the EUV spectrometers are established to monitor and study the impurity behavior
The black circle points with solid line represent the relative responsivity obtained via the synchrotron radiation (SR) light source measurement which is described in section II B and it shows the responsivity between 175 and 435 Å varies by factor of ∼ 46
The first method was implemented by measuring the responsivity curve of the grating with synchrotron radiation light source
Summary
The extreme ultraviolet (EUV) spectroscopic measurements are meaningful in laboratory plasma researches due to the diagnostic value of plasma conditions.[1,2] At magnetic confinement fusion devices, the EUV spectrometers are established to monitor and study the impurity behavior. The electron temperature and electron density could be obtained from measurement of line intensity ratios and line profiles, respectively.[3,4] For laboratory astrophysics surveys, the high-resolution EUV measurements help to discover a number of coronal lines which are not yet identified in the current databases.[5,6] In addition, the intensity ratios of iron lines are good candidates to determine the plasma density or even the magnetic field strength in the solar corona.[7,8] For the extensive utilization in plasma diagnostics, a portable high-resolution extreme ultraviolet spectrometer has been designed and developed at Shanghai electron beam ions trap (EBIT) laboratory[9] since 2014
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