DESIGN OF PROTON FFAG ACCELERATORS.
When designing a FFAG accelerator for protons we found convenient to follow this procedure [1]. (1) We assume a Non-Scaling Lattice (NSL) because the aim is toward a compact layout, though we are aware of the issue of multiple resonance crossing. (2) We take a periodic sequence of FDF triplets as these have been proven to exhibit a very small dispersion function. (3) The reference trajectory is taken to be the injection orbit that corresponds to the lowest value of the acceleration momentum range. (4) Finally, the magnets in the triplet have all a linear field profile. We have indeed found recently [2,3] that the Adjusted Field Profile (AFP) to cancel the horizontal chromaticity is exceedingly non-linear and it causes a too large betatron tune variation with the amplitude of motion. A sequence of FDF triplets is shown in Figure 1. They are made of sector magnets having parallel entrance and exit planes facing each other. Only for the injection orbit the trajectory in the magnets is made of arcs of circle. The magnets have sharp edges and there is no entrance or exit angle only for the reference (injection) orbit [4]. This solution minimizes magnet width, has the most stable momentum range, and allows longer drifts between triplets. Figure 2 shows a schematic of a FDF triplet with all the essential parameters. It is defined by 8 variables: the long drift S, the short drift g, the length L{sub F}, the bending field B, on the reference orbit, and the field gradient G{sub F} of the focusing (F) sector magnets, and the same quantities L{sub D}, B{sub D} and G{sub D} of the de-focusing sector magnet (D). To these we need to add the particle magnetic rigidity Bp (or equivalently the momentum p) and the full ring circumference C. We have thus a total of 10 variables that define uniquely the lattice of the FFAG ring for a given particle energy.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- Sponsoring Organization:
- DOE/SC
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 878152
- Report Number(s):
- BNL-75634-2006-CP; R&D Project: 18026; KB0202011; TRN: US0602025
- Resource Relation:
- Conference: 2005 FIXED-FIELD ALTERNATING GRADIENT WORKSHOP (FFAG'05); OSAKA, JAPAN; 20051204 through 20051209
- Country of Publication:
- United States
- Language:
- English
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