High-Current Pulsed ECR Ion Sources

At the present time, some ECR ion sources use a high-frequency powerful microwave radiation of modern gyrotrons for plasma heating. Due to high radiation power, such systems mainly operate in a pulsed mode. This type of ECR ion sources was developed at the Institute of Applied Physics of the Russian Academy of Sciences (IAP RAS), and most experimental research was performed at the SMIS 37 facility, at which 37 gyrotrons with 37.5- and 75-GHz frequencies and 100- and 200-kW maximum powers, respectively, were used for plasma production. Such heating microwaves allow creating plasma with unique parameters: electron density >1013 cm–3, electron temperature of 50–300 eV, and ion temperature of about 1 eV. The principal difference between these systems and conventional ECR sources is a so-called quasi-gas-dynamic regime of plasma confinement. In accordance with the confinement regime, such sources have been called “gas-dynamic ECR sources.” Typically, plasma lifetime in such systems is about several tens of microseconds, which, in combination with the high plasma density, leads to the formation of plasma fluxes from a trap with a density of up to 1–10 A/cm2. The possibility of production of multiply charged ion beams (nitrogen, argon) and proton (or deuterium) beams with currents of up to a few hundred mA and normalized rms emittance of about 0.1π mm mrad was demonstrated. The next step in the research is a transition to continuous wave operation. For this purpose, a new experimental facility is under construction at the IAP RAS. A future source will utilize 28- and 37.5-GHz gyrotron radiation for plasma heating. An overview of the obtained results and the status of the new source development is presented.