MI Gap Clearing Kicker Magnet Design Review
The kicker system requirements were originally conceived for the NOvA project. NOvA is a neutrino experiment located in Minnesota. To achieve the desired neutrino flux several upgrades are required to the accelerator complex. The Recycler will be used as a proton pre-injector for the Main Injector (MI). As the Recycler is the same size as the MI, it is possible to do a single turn fill ({approx}11 {micro}sec), minimizing the proton injection time in the MI cycle and maximizing the protons on target. The Recycler can then be filled with beam while the MI is ramping to extract beam to the target. To do this requires two new transfer lines. The existing Recycler injection line was designed for 10{pi} pbar beams, not the 20{pi} proton beams we anticipate from the Booster. The existing Recycler extraction line allows for proton injection through the MI, while we want direct injection from the Booster. These two lines will be decommissioned. The new injection line from the MI8 line into the Recycler will start at 848 and end with injection kickers at RR104. The new extraction line in the RR30 straight section will start with a new extraction kicker at RR232 and end with new MI injection kickers at MI308. Finally, to reduce beam loss activation in the enclosure, a new gap clearing kicker will be used to extract uncaptured beam created during the slip stack injection process down the existing dump line. It was suggested that the MI could benefit from this type of system immediately. This led to the early installation of the gap clearing system in the MI, followed by moving the system to Recycler during NOvA. The specifications also changed during this process. Initially the rise and fall time requirements were 38 ns and the field stability was {+-}1%. The 38 ns is based on having a gap of 2 RF buckets between injections. (There are 84 RF buckets that can be filled from the Booster for each injection, but 82 would be filled with beam. MI and Recycler contain 588 RF buckets.) A rough cost/benefit analysis showed that increasing the number of empty buckets to 3 decreased the kicker system cost by {approx}30%. This could be done while not extending the running time since this is only a 1% reduction in protons per pulse, hence the rise and fall time are now 57 ns. Additionally, the {+-}1% tolerance would have required a fast correction kicker while {+-}3% could be achieved without this kicker. The loosened tolerance was based on experience on wide band damping systems in the MI. A higher power wideband damping system is a better use of the resources as it can be used to correct for multiple sources of emittance growth. Finally, with the use of this system for MI instead of Recycler, the required strength grew from 1.2 mrad to 1.7 mrad. The final requirements for this kicker are listed.
- Research Organization:
- Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC02-07CH11359
- OSTI ID:
- 960265
- Report Number(s):
- FERMILAB-TM-2429-AD; TRN: US0904415
- Country of Publication:
- United States
- Language:
- English
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