High current ECR source of multicharged ion beams

TLDR: In this article, a quasi-gas-dynamic ECR source with axisymmetric configuration has been proposed, which can achieve high flux density and high power in a cusp magnetic trap.

Abstract: Great demand for multicharged ion (MCI) sources stimulated investigation of new methods of producing plasma by means of ECR gas discharge in magnetic traps. The authors of this research propose a new type of pulsed sources of MCI, namely, a quasi-gasdynamic ECR source. Its main difference from the classical ECR MCI sources is a different, quasi-gasdynamic regime of plasma confinement in a magnetic trap. A zero-dimensional model describing gas breakdown, formation of charge state distribution in a plasma, and plasma flux through the plugs of the trap was constructed. A wide spectrum of model experimental studies was covered. Plasma was produced and heated by a pulsed (1 ms) gyrotron at the frequency of 37.5 GHz and power of 100 kW in a cusp magnetic trap. Such a trap has axisymmetric configuration and allows one to realize a quasi-gasdynamic regime of confinement with reliable stabilization of MHD perturbations. It was demonstrated that with such a confinement regime it is possible to generate multicharged ions and create intense (more than 1 A/cm2) ion fluxes through the trap plugs. Comparison of results of calculations and data of experiments shows that they are in a good agreement, which allows us to predict with a high degree of certainty creation of an ECR source of a new generation. The data obtained were used to design a pulsed quasi-gasdynamic ECR MCI source with pumping at the frequency of 100 GHz, effective trap size 1 m, average ion charge in plasma comparable with that in the best classical MCI ECR sources but with an order of magnitude higher flux density and absolute magnitude of plasma flux from a trap. Creation of intense plasma fluxes allows one to extract high-current MCI beams of high brightness. Transverse homogeneity of a plasma flux makes it possible to use a multi-aperture extraction system for formation of broad intense MCI beams.