CEBAF commissioning status

CEBAF is a 4 GeV, 200 μA CW electron accelerator, recirculating the beam five times through two superconducting linacs. The accelerator itself is not due to be completed until January 1994 but CEBAF has been accelerating beams for more than a year and has already validated many of the design concepts. In the injector, 340 μA have been accelerated to 45 MeV. In a recirculation experiment, 215 μA have been accelerated to 80 MeV, demonstrating by extrapolation that the full 5 pass machine will operate well below the recirculating beam break-up threshold. In the north linac, beam has been accelerated to over 245 MeV using 99 superconducting cavities at an average gradient of 5 MeV/m. The beam characteristics mostly meet or exceed specifications. Beam has been taken around 135° of the first arc and the optical properties have been studied. High current tests in the north linac resulted in several runs of more than 100 μA being accelerated through more than 120 superconducting cavities