The measurement of the axially lost electron energy distribution escaping from a minimum-B electron cyclotron resonance ion source in the range of 4–800 keV is reported. The experiments have revealed the existence of a hump at 150–300 keV energy, containing up to 15% of the lost electrons and carrying up to 30% of the measured energy losses. The mean energy of the hump is independent of the microwave power, frequency and neutral gas pressure but increases with the magnetic field strength, most importantly with the value of the minimum-B field. Experiments in pulsed operation mode have indicated the presence of the hump only when microwave power is applied, confirming that the origin of the hump is radio-frequency-induced momentum space diffusion. A possible mechanism of the hump formation is considered based on the quasi-linear model of plasma–wave interaction.
To investigate the hot electron population and the appearance of kinetic 18 instabilities in highly charged electron cyclotron resonance ion source (ECRIS), the 19 axially emitted bremsstrahlung spectra and microwave bursts emitted from ECRIS 20 plasma were synchronously measured on SECRAL-II (Superconducting ECR ion source 21 with Advanced design in Lanzhou No. II) ion source with various magnetic field 22 configurations. The experimental results show that when the ratio of the minimum 23 field to the resonance field (i.e. B min /B ecr ) is less than ~0.8, the bremsstrahlung 24 42
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.