Radial Profile Estimation of Electron Density in a Linear Plasma Device NUMBER Using a Single Line-of-Sight Signal

Abstract

In this paper, a method for estimating the radial profile of electron density n e using a single line-of-sight signal by the He I line intensity ratio method is proposed. By applying this method to cylindrical helium plasma, in which electron temperature was almost uniform and density was uniform in the center, we tried to estimate the parameters representing spatial distribution. It was confirmed that a good distribution estimation result could be obtained by considering the sensitivity factor, the rate at which the line intensity ratio changes as the parameters change, during optimization. Two methods of considering a sensitivity factor are proposed: using the best combination of intensity ratios for analysis in terms of the sensitivity factor, and weighting the objective function using the sensitivity factor. The former method can be analyzed in short computational time, although its applicability is limited. The latter method can be used when it is not obvious which set of intensity ratios is best to use, although it takes more computational time compared with the former method. Both methods reproduce the parameter of a radial density profile.

Helium line emission spectroscopy to measure plasma parameters using modeling and machine learning in low-temperature plasmas

“…Except for (c), He is a minor or impurity species in hydrogen isotope plasma. Due to the importance of He in fusion experiments, fundamental research on He I LIRs has been intensively conducted in linear plasma devices such as PISCES-A [69], PISCES-B [70], NAGDIS-I [71,72], NAGDIS-II [73], MAP-II [74], DT-ALPHA [75], Magnum-PSI [76], NUMBER [77], a helicon plasma device [78], and microwave-generated plasmas [79]. For LIRs using a He beam, it is necessary to use a time-dependent model to take into account the long relaxation time of the metastable state in the triplet system [80].…”

Structure of intermittent variation of floating potential in a converging field following a magnetic beach ECR plasma source

“…Cylindrical magnetized plasmas are widely used as simple well-defined targets for basic plasma physics experiments [1][2][3][4] as well as for divertor plasma simulating experiments. [5][6][7][8][9][10] Then converging magnetic field configuration is often adopted.…”

“…[5][6][7][8][9][10] Then converging magnetic field configuration is often adopted. 3,4,[7][8][9][10] This is because the field strength in the plasma source region is sometimes lower than that required for the test region due to the suitable range of magnetic field for each plasma production method. 11) Measurement and control of temperature and density in the high field test region are important issues.…”