| Paper | Title | Page |
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| TUPRO075 | Initial Analysis of the 4D Transfer Map in the Emma Non-Scaling Fixed Field Alternating Gradient Accelerator | 1214 |
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Funding: STFC The EMMA non-scaling Fixed Field Alternating Gradient accelerator (ns FFAG) is a ring consisting of 42 quadrupole pairs. The dipole fields which guide particles around the ring are arrived at through offsetting the quadrupoles from a reference axis. In the ideal case, first order 4D transfer maps will describe the turn by turn progression of a particle bunch in transverse phase space. This contribution sees the use of experimental data to calculate the 4D transfer map for EMMA at several different momenta, and a comparison made with maps produced through simulation. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRO075 | |
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| TUPRO026 | Possible Beam-beam and Levelling Scenarios for HL-LHC | 1071 |
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Funding: Research supported by EU FP7 HiLumi LHC - Grant Agreement 284404 The upgrade of the LHC from the current set-up to high luminosity performances will provide new challenges from the point of view of beam-beam as well as other collective effects and luminosity levelling. We present the current possibilities for doing luminosity levelling for HL-LHC. We explore the merits and drawbacks of each option and briefly discuss the operational implications. The simplest option being levelling with an offset between the two beams. In particular, we look at the possibility of using flat beams in the IPs for all the available options and investigate their benefits and drawbacks, using the code COMBI. Flat beams would allow an additional degree of freedom, with the levelling only required in one of the planes at any given IP. To this end, various scenarios are looked at, both with and without crab cavities. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRO026 | |
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| THPRO052 | Beam Physics Commissioning of VELA at Daresbury Laboratory | 2986 |
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| A user facility VELA (Versatile Electron Linear Accelerator) based on an RF photoinjector has been commissioned at Daresbury Laboratory in April 2013, providing beam to first users in September 2013. Machine study runs in 2013-2014 have concentrated on characterisation of main beam parameters like bunch charge, its momentum, beam emittance and dependence of these parameters on the launching RF phase. Major efforts have been also concentrated on investigation of the dark current from the gun and its dependence on the RF amplitude. Significant time has been dedicated to investigation of relative stability of LLRF and drive laser having significant impact on the overall machine stability. We present here the results of these studies. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO052 | |
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| THPRO084 | Beam Dynamics Observations of Slow Integer Tune Crossing in EMMA | 3082 |
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| When the betatron tune is an integer in a cyclical accelerator, dipole-field errors can drive the coherent addition of betatron amplitude to the bunch eventually causing particle loss. Transverse integer tune crossing in a linear non-scaling FFAG is inevitable due to finite chromaticity. In EMMA (Electron Machine with Many Applications), as many as 6 integers may be crossed is as little as 6 turns at maximum acceleration over the 10 – 20 MeV energy range. This fast integer tune crossing, of the order 1 integer per turn, was shown to have little effect on the coherent amplitude growth and charge loss rate. Slower acceleration inside an RF bucket in EMMA allowed the experimental exploration of slower integer tune crossing speeds, of the order of a factor ten slower. The effect on the coherent oscillation amplitude was observed and the charge loss at integer tune crossings indicated resonant effects on the bunch. Simulations in Zgoubi allowed a more detailed analysis and the mechanism of slower resonance crossing in a non-scaling FFAG is discussed, including the importance of coupled longitudinal-transverse decoherence on the effective emittance. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO084 | |
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