AGS tune jump system to cross horizontal depolarization resonances overview
Two partial snakes overcome the vertical depolarizing resonances in the AGS. But a new type of depolarizing intrinsic resonance from horizontal motion appeared. We reduce these using horizontal tune jumps timed to these resonances. We gain a factor of six in crossing rate with a tune jump of 0.05 in 100 {micro}s. Two quadrapoles, we described in 2009, pulse 42 times, the current matching beam energy. The power supplies for these quads are described in detail elsewhere in this conference. The controls for the Jump Quad system is based on a BNL designed Quad Function Generator. Two modules are used; one for timing, and one to supply reference voltages. Synchronization is provided by a proprietary serial bus, the Event Link. The AgsTuneJump application predicts the times of the resonances during the AGS cycle and calculates the power supply trigger times from externally collected tune and energy versus time data and the Low and High PS voltage functions from a voltage to current model of the power supply. The system was commissioned during runs 09 & 10 and is operational. Many beam effects are described elsewhere. The TuneJump system has worked well and has caused little trouble save for the perturbations in the lattice having such a large effect due to our need to run with the vertical tune within a few thousandths of the integer tune. As these problems were mostly sorted out by correcting the 6th harmonic orbit distortions which caused a large 18 theta beta wave. Also running with minimal chromaticity reduces emittance growth. There are still small beta waves which are being addressed. The timing of the pulses is still being investigated, but as each crossing causes minimal polarization loss, this is a lengthy process.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States). Alternating Gradient Synchrotron
- Sponsoring Organization:
- DOE - Office Of Science
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 1012594
- Report Number(s):
- BNL-94173-2011-CP; R&D Project: KBCH139; 18031; KB0202011; TRN: US1102336
- Resource Relation:
- Conference: 2011 Particle Accelerator Conference (PAC'11); New York, NY; 20110328 through 20110401
- Country of Publication:
- United States
- Language:
- English
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