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.

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.

Electron Cyclotron Resonance (ECR) ion Sources are the most performing machines for the production of intense beams of multi-charged ions in fundamental science, applied physics and industry. Investigation of plasma dynamics in ECRIS still remains a challenge. A better comprehension of electron heating, ionization and diffusion processes, ion confinement and ion beam formation is mandatory in order to increase ECRIS performances both in terms of output beams currents, charge states, beam quality (emittance minimization, beam halos suppression, etc.). Numerical solution of Vlasov equation via kinetic codes coupled to FEM solvers is ongoing at INFN-LNS, based on a PIC strategy. Preliminary results of the modeling will be shown about wave-plasma interaction and electron-ion confinement: the obtained results are very helpful to better understand the influence of the different parameters (especially RF frequency and power) on the ion beam formation mechanism.

Experiments have recently demonstrated that kinetic instabilities occurring in magnetoplasma are huge limiting factors to the flux of highly charged ion beams extracted from ECR ion sources. Recently, it has been shown that the two-frequency-heating (TFH) mode has the proven potential to mitigate these instabilities. Since the fundamental physical mechanism of TFH is still unclear, a deeper experimental investigation is necessary. At ATOMKI-Debrecen, the effect on the kinetic instabilities of an argon plasma in a 'two-close-frequency heating' scheme has been explored for the first time by using a frequency gap smaller than 1 GHz (i.e. operating in the so-called twoclosed-frequency heating mode). A special multi-diagnostics setup has been designed and implemented. In this paper, we will show the data collected by a two-pin, plasma-chamber immersed antenna connected to an RF detector diode and/or to a spectrum analyzer for the detection of plasma radio-self-emission when varying the pumping frequency in single versus double frequency heating mode. Data have been collected simultaneously to the beam extraction and for different frequency gaps and relative power balances. The turbulent regime of the plasma has been tentatively described in a quantitative way, according to the properties of the plasma self-emitted RF spectrum. The measurements show that plasma self-emitted radiation emerges from the internal ECR region everytime (i.e. below the lower pumping frequency) but the almost total instability damping can be effective for some specific combinations of frequency-gap and power balance, thus eventually improving the plasma confinement. Keywords: electron cyclotron resonance ion source, plasma diagnostics, kinetic plasma instability 'scaling laws' [1]. More recently, this approach has become more difficult because of the technological limits. A deeper knowledge of plasma parameters (electron density, temperature and charge state distribution (CSD)) is thus fundamental: the characteristics of the extracted beam (in terms of current intensity and production of high charge states) are directly connected to plasma parameters and structure. Several experiments have, in fact, demonstrated that plasma instabilities limit the flux of highly charged ions extracted from ECR ion sources, causing beam ripple [2][3][4]. The