K. FURUKAWA (LINAC COMMISSIONING GROUP, KEK)
KEK 2.5-GeV electron linac was upgraded to 8-GeV for the KEK B-Factory (KEKB) project. During the commissioning of the upgraded linac, even continuing SOR ring injections, we had achieved a primary electron beam with 10-nC (6.24 x 10^10) per bunch up to 3.5-GeV for positron generation. This could be classified as one of the brightest S-band linac's. Since the KEKB rings were completed in December 1998, those 3.5-GeV position and 8-GeV electron beams have been injected with an excellent performance. Moreover, we have succeeded in switching among the high-intensity beams for KEKB and 2.5-GeV electron beams for two SOR rings with sufficient reproducibility. After the commissioning of the KEKB ring started, we have launched a project to stabilize the intensity and quality of the high-current beams furthermore, and have accomplished it investigating every conceivable aspect. During this improvement, we had valuable experiences on tolerance studies and stabilization technique of the timing and rf systems. We also gained a knowledge on the physical phenomena of the beams particularly of an emittance growth. They are indispensable for the design and construction of the next generation accelerators such as a linear collider, an FEL and an injector for super-high-luminosity machines.
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