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| TUAM5X01 | Space Charge Driven Beam Loss for Cooled Beams and Mitigation Measures in the CERN Low Energy Ion Ring | 272 |
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| The performance of the CERN Low Energy Ion Ring (LEIR) with electron cooled lead ion beams is presently limited by losses, which occur during RF capture and the first part of acceleration. Extensive experimental studies performed in 2015 indicate that the losses are caused by the interplay of betatron resonances and the direct space charge detuning, which is significantly enhanced during bunching. Mitigation measures have already been identified and successfully tested, such as reducing the peak line charge density after RF capture, i.e. increasing the rms longitudinal emittance, and compensating third order resonances using existing harmonic sextupole correctors. New record intensities at extraction have been achieved. This talk describes the main experimental results from the 2015 measurement campaign including already implemented mitigation measures and the proposed strategy for even further increasing the LEIR intensity reach in the future. | ||
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Slides TUAM5X01 [8.803 MB] | |
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-HB2016-TUAM5X01 | |
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| TUAM6X01 | First Analysis of the Space Charge Effects on a Third Order Coupled Resonance | 278 |
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| The effect of space charge on bunches stored for long term in a nonlinear lattice can be severe for beam survival. This may be the case in projects as SIS100 at GSI or LIU at CERN. In 2012, for the first time, the effect of space charge on a normal third order coupled resonance was investigated at the CERN-PS. The experimental results have highlighted an unprecedented asymmetric beam response: in the vertical plane the beam exhibits a thick halo, while the horizontal profile has only core growth. The quest for explaining these results requires a journey through the 4 dimensional dynamics of the coupled resonance investigating the fixed-lines, and requires a detailed code-experiment benchmarking also including beam profile benchmarking. This proceeding gives a short summary of the experimental results of the 2012 PS measurements, and address an interpretation based on the dynamics the fixed-lines. | ||
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Slides TUAM6X01 [7.183 MB] | |
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-HB2016-TUAM6X01 | |
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| TUAM7X01 | Intensity Effects in the Formation of Stable Islands in Phase Space During the Multi-Turn Extraction Process at the CERN PS | 283 |
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| The CERN PS utilises a multi-turn extraction (MTE) scheme to stretch the beam pulse length to optimise the filling process of the SPS. MTE is a novel technique to split a beam in transverse phase space into nonlinear stable islands. The recent experimental results indicate that the positions of the islands depend on the total beam intensity. Particle simulations have been performed to understand the detailed mechanism of the intensity dependence. The analysis carried out so far suggests space charge effects through image charges and image currents on the vacuum chamber and the magnets’ iron cores dominate the observed behaviour. In this talk, the latest analysis with realistic modelling of the beam environment is discussed and it is shown how this further improves the understanding of intensity effects in MTE. | ||
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Slides TUAM7X01 [1.682 MB] | |
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-HB2016-TUAM7X01 | |
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TUAM8X01 |
Beam-Beam Effects in the Large Hadron Collider | |
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| The Large Hadron Collider (LHC) is operating at an energy of 6.5 TeV and in 25 ns bunch spacing very close to the design values. For the 2015 physics RUN beam-beam effects have been kept weak in order to gain experience with other effects (i.e. impedance, e-cloud). The 2016 physics run will perform at stronger long-range effects. Several experiments devoted to highlight the beam-beam limits have been carried out during the year in order to define possible future scenarios with the aim to maximize the integrated luminosity. In this paper the beam-beam effects observed during physics fills and devoted experiments will be presented with considerations on the possible limitations for future operation of the LHC and extrapolations to HL-LHC. | ||
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Slides TUAM8X01 [8.146 MB] | |
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