A New Method for Enhancing the Performances of Conventional B-Geometry ECR Ion Sources

Abstract

The viability of the "volume"-effect for enhancing the high-charge-state populations and intensities of beams extracted from ECR ion sources has been clearly demonstrated at several laboratories. Enlarged ECR zones have been achieved by engineering the central magnetic field so that it is flat and in resonance with single-frequency rf power or alternatively, by using multiple frequency or broadband techniques to enlarge the ECR volumes within these sources. For example, the performances of conventional B-geometry sources have been ameliorated at several laboratories through the use of multiple frequency rf power sources. Although the multiple-discrete frequency method is a very effective means for enhancing the performances of traditional-B geometry sources, the practical application of the technique is very costly, requiring multiple independent single-frequency rf power supplies and serious modification to the rf injection systems of these sources. Broadband sources of rf power offer an low-cost and more effective alternative for increasing the physical sizes of the ECR volumes within these sources. Although, previously suggested, here-to-fore, broadband microwave power sources have not been available for use to the ECR ion source community. A special programmable additive "white" Gaussian noise generator (AWGNG) system for injecting broadband rf power into these sources has been conceived and developed in conjunction with a commercial firm for such applications. The noise generator, in combination with an external local oscillator, can be used to generate broadband microwave radiation for amplification with a TWT without having to modify the injection systems of these sources. The AWGNG and its use for enhancing the performances of conventional B-geometry ECR ion sources will be described in this document. PACS: 07.77.Ka.; 29.25.Ni.; 41.75.Ak.; 52.25.Jm.; 52.25.Xz.; 52.50.Qt.