Electromagnetic diagnostics of ECR-Ion Sources plasmas: optical/X-ray imaging and spectroscopy

Abstract

Magnetoplasmas in ECR-Ion Sources are excited from gaseous elements or vapours by microwaves in the range 2.45–28 GHz via Electron Cyclotron Resonance. A B-minimum, magnetohydrodynamic stable configuration is used for trapping the plasma. The values of plasma density, temperature and confinement times are typically ne= 1011−1013 cm−3, 01 eV<Te<10 keV, 0.001<tc<1 s. At INFN-LNS several diagnostics tools have been developed for probing the electromagnetic emission of such plasmas, in the optical/X-ray domain. Fast Silicon Drift detectors with high energy resolution of 125 eV at 5.9 keV have been used for the characterization of plasma emission at 02<E<3 keV . In the domain 0.4–17 keV an X-ray pin-hole camera technique has allowed space resolved X-ray spectroscopy with a spatial resolution down to 30 μm and an energy resolution down to 140 eV at 5.9 keV . In parallel, imaging in the optical range and spectroscopic measurements have been carried out. Relative abundances of H/H2 atoms/molecules in the plasmas have been measured for different values of neutral pressure, microwave power and magnetic field profile (they are critical for high-power proton sources).

High resolution spectropolarimetry: from Astrophysics to ECR plasmas

“…However, present OES measurements are characterized by the absence of spatial resolution. An example is shown in [8] where the presence of lines from both atomic and molecular transitions in hydrogen spectra testifies the limits in spatially separating hot and cold plasma regions. A further limit of plasma OES is represented by low spectral resolution: spectra were obtained with R = 250, which means that it is not possible to identify lines separated less than 2 nm at 500 nm.…”

Laboratory plasmas for high-energy astrophysics: A method to measure effective Landé g-factors

“…Plasma emission from X-ray to radio frequencies can in principle be detected (e.g. Mascali et al 2017).…”

Quantitative analysis of an ECR Ar plasma structure by X-ray spectroscopy at high spatial resolution

“…X-ray plasma diagnostics for ECR (Electron Cyclotron Resonance) ion sources and traps have been developed along the years allowing volumetric characterization of the plasma [5][6][7][8][9][10][11]. At INFN-LNS several non invasive plasma diagnostic tools have been developed [12], with advanced analytical methods [13]. Among the others, the innovative diagnostic tool consisting of a lead pin-hole coupled with a X-ray CCD camera has been developed and implemented in collaboration with ATOMKI laboratories: this tool is able to perform high spatially-resolved spectroscopy in the soft X-ray domain and so to investigate the plasma spatial structure and confinement.…”