Speaker: Georg H. Hoffstaetter
Abstract: The first multi-turn Energy Recover Linac (ERL), CBETA, that recovers beam energy in Superconducting Radio Frequency (SRF) resonators utilizes a Fixed Field Alternating-gradient (FFA) optics in its return loop. It has an energy acceptance of nearly 4 and transports beams at 42, 78, 114, and 150 MeV simultaniously. It has been designed, constructed, and commissioned to low currents by Brookhaven National Laboratory (BNL) and Cornell University. An overview of this project will be presented, including design parameters, aspects of implementation, and milestones of construction will be shown, including ERL efficiency of 99.4% in a 1-turn ERL arrangement and simultaneous orbits of 7 beams in one beam-transport system during 4-turn ERL operation.
7 replies on “CBETA commissioning and relation to the EIC”
Thanks, Georg, for the nice talk. Can you say more about the micro-bunching? How is it expected to scale with bunch charge? How will it be mitigated? What is the phase slip factor? Is it tunable?
I believe CBETA is a treasure trove as you said and hope more contributions to the community. My naive question is why ERL based FCC-ee can make the power consumption one order smaller? Is it because of small emittance? Second question is about the arc. I understand that FFA is not considered at the moment. However, if FFA arc is used, what sort of momentum acceptance is required?
Nice talk! I’m just curious about these: 1. The measured tune per cell looks very well agreed with the predictions. How is it measured? 2. Vertically, the orbits of different energies offset from each other. Does the machine also have a vertical dispersion?
Another question: how is the orbit correction done simultaneously for 4 different energies?
Both Stephen Brooks and I have talks on Wednesday addressing this.
There were two methods used for the tune measurement. One was to kick the beam in the splitter lines and fit the result to a sine wave. Another was to do an FFT, I believe a kick in the splitters was also used, but am not sure.
By design there is no vertical dispersion in the lines. Slide 23 is the horizontal orbit. Slide 25 has artificial offset to make the different energies visible; I believe the lines are all actually centered at zero.
I see. Thanks.