Operation of the SERSE superconducting electron cyclotron resonance ion source at 28 GHz

Abstract

The SERSE source [P. Ludwig et al., Rev. Sci. Instrum. 69, 4082 (1998), and references therein] is a superconducting electron cyclotron resonance (ECR) ion source, operating at the Laboratori Nazionali del Sud in Catania since 1998; it is currently used as the main injector for the K-800 superconducting cyclotron. Its high magnetic field provides a high plasma confinement and large currents of highly charged ions, as compared to conventional sources. It can efficiently operate at the microwave frequency of 14 and 18 GHz [S. Gammino and G. Ciavola, Rev. Sci. Instrum. 71, 631 (2000); S. Gammino et al., ibid.70, 3577 (1999)] and has been used as a test bench for injection at 28 GHz. High-frequency operation is expected to create a higher plasma density, thus resulting in larger currents of multiply charged ions. In this article, we report the first operation of an ECR ion source at 28 GHz by using a gyrotron. The gyrotron itself and the waveguide line are described, along with the operational results (in xenon gas for the sake of simplicity). Given the limited amount of power (about 4 kW), which can be injected in the plasma chamber during dc-mode operation, the results are less outstanding than in the pulsed mode (up to 6.5 kW). However, in both cases the beam intensities are far better than the ones obtained by the other ECR ion sources operating at lower frequencies.