Electron cyclotron resonance ion source plasma characterization by energy dispersive x-ray imaging

Abstract

Pinhole and CCD based quasi-optical X-ray imaging technique was applied to investigate the plasma of an Electron Cyclotron Resonance Ion Source. Spectrally integrated and energy resolved images were taken from an axial perspective. The comparison of integrated images taken of argon plasma highlights the structural changes affected by some ECRIS setting parameters, like strength of the axial magnetic confinement, RF frequency and microwave power. Photon counting analysis gives precise intensity distribution of the X-ray emitted by the argon plasma and by the plasma chamber walls. This advanced technique points out that the spatial positions of the electron losses are strongly determined by the kinetic energy of the electrons themselves to be lost and also shows evidences how strongly the plasma distribution is affected by slight changes in the RF frequency.

Innovative Analytical Method for X-Ray Imaging and Space-Resolved Spectroscopy of ECR Plasmas

“…Other details about the setup are described in [27]. By this system the pin-hole camera was operated up to 200 W total incident power in the plasma, namely one order of magnitude higher compared to the previous measurements (where the pumping power was limited to 30 W [20,21]). This way, both stable and turbulent plasma regimes (typically triggered above certain power thresholds [28,29]) have been investigated [30,31], also studying new plasma heating methods [32,33].…”

“…High precision X-ray measurements can be also performed in a spatially-resolved way by means of the powerful X-ray pin-hole camera tool which allows to perform high resolution spatially-resolved spectroscopy. Even if our teams have already been using the X-ray camera techniques combined with pinholes since more than 15 years [16][17][18][19][20][21][22], and this method has been routinely used in several other laboratories (for example at Z-machines [23][24][25][26]), recently both the tool [27] and the advanced analytical method have been drastically improved. In this paper the on-purpose developed analytical method will be presented.…”

Innovative launching schemes in ECR ion sources

“…In these "big-size" scenarios, wellestablished optical techniques (e. g. grooved mirrors, lenses and grating polycromator), were adopted to optimize the O-X-B conversion, in terms of wave polarization and incidence angle. On the contrary, in ECRIS, the pumping wavelength is comparable with the plasma radius [14] and density scale-length, thus prohibiting any ray tracing approach. Full-wave calculations must be applied to simulate the wave behaviour in the plasma [15,16].…”

Innovative Analytical Method for X-ray Imaging and Space-Resolved Spectroscopy of ECR Plasmas

“…High-precision X-ray measurements can be also performed in a spatially resolved way by means of the powerful X-ray pin-hole camera tool, which allows us to perform high-resolution, spatially resolved spectroscopy. Even if our teams have already been using the X-ray camera techniques combined with pinholes for more than 15 years [14][15][16][17][18][19], and this method has been routinely used in several other laboratories (for example, at Z-machines [20][21][22][23] or in plasma fusion devices [24][25][26][27]), recently, both the tool [28] and the advanced analytical method have been drastically improved.…”