Paper | Title | Page |
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TUPEA008 | Physics of the AWAKE Project | 1179 |
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The goal of the AWKAKE collaboration is the study of plasma wakefields driven by proton (p+) bunches through experiments, simulations and theory. Proton bunches are interesting wakefield drivers because they can be ultra-relativistic (TeVs/p+) and carry large amounts of energy (>kJ). It was demonstrated in simulations* that acceleration of an electron (e-) bunch from 10GeV to >500GeV can be achieved in ~500m of plasma driven by a 1TeV, 100micron-long, bunch with 1011 p+. Such short p+ bunches do not exist today. It was suggested** that a p+ bunch long compared to the plasma period can transversely self-modulate and resonantly drive wakefields to large amplitudes (~GV/m). Initial experiments based on self-modulation instability (SMI) will use single 12cm-long CERN SPS bunches with 1-3·1011, 450GeV p+ to study physics of SMI. With a plasma density of 7·1014/cc the plasma wave and modulation period is 1.3mm. The SMI saturates after ~3m with amplitude in the GV/m range. Later a low energy (~10MeV) witness e- bunch will be injected at the SMI saturation point. Energy gain over ~7m of plasma can reach the GeV level. Translation from physics to experimental plan and setup will be presented.
* A. Caldwell et al., Nature Physics 5, 363 (2009) ** N. Kumar et al., Phys. Rev. Lett. 104, 255003 (2010) |
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TUPEA045 | Self-Modulation and Hosing Instability of Slac Electron and Positron Bunches in Plasmas | 1235 |
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Funding: This work has been partially supported by Humboldt Foundation. The understanding of the self-modulation (SMI) and hosing (HI) instabilities is critical for the success of the upcoming proton driven plasma wakefield acceleration experiments at CERN*. The use of long SLAC electron and positron bunches provides the possibility of understanding experimentally the interplay between SMI and HI. In this work we perform particle-in-cell simulations with the code OSIRIS with parameters that will be available for experiments at SLAC in 2013. We show that the SMI of 20 GeV lepton bunches can grow and saturate in less than 15 cm. Up to 8 GeV energy gain/loss could be observed after a meter long plasma. The HI can also be effectively mitigated by seeding the SMI using bunches with short rise times**. We also show analytically and numerically that in the linear regime and after saturation of the SMI the HI can be suppressed by a plasma-BNS damping analogue. Several diagnostics that could be used in experiments to measure the SMI development and these effects are also explored. *G. Xia et al., J. Plasma Phys., 1-7 (2012). **J. Vieira et al., Phys. Plasmas 19, 063105 (2012). |
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TUPEA051 | Beam Transfer Line Design for a Plasma Wakefield Acceleration Experiment (AWAKE) at the CERN SPS | 1247 |
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The world’s first proton driven plasma wakefield acceleration experiment is presently being studied at CERN. The experiment will use a high energy proton beam extracted from the SPS as driver. Two possible locations for installing the AWAKE facility are considered: the West Area and the CNGS long baseline beam-line. The previous transfer line from the SPS to the West Area was completely dismantled in 2000 and it would need to be fully re-designed and re-built. For this option, geometric constraints for radio protection reasons would limit the maximum proton beam energy to 300 GeV. The existing CNGS line could be used by applying only minor changes to the final part of the lattice for the final focusing and the interface between the proton beam and the laser, required for plasma ionisation and bunch-modulation seeding. The beam line design studies performed for the two options are presented. | ||
TUPME020 | Design of a TeV Beam Driven Plasma-wakefield Linear Collider | 1613 |
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Funding: This work is supported by the Research Council of Norway and U.S. Department of Energy under contract number DE-AC02-76SF00515. A novel design of a 500 GeV c.m. beam-driven PWFA linear collider with effective accelerating gradient on the order of 1 GV/m and extendable in the multi-TeV energy range is presented. The main bunches collide in CW mode at several kHz repetition frequency. They are accelerated and focused with several GV/m fields generated in plasma cells by drive bunches with very good transfer efficiency. The drive bunches are themselves accelerated by a CW superconducting rf recirculating linac. We consider the overall optimizations for the proposed design, compare the efficiency with similar collider designs like ILC and CLIC and we outline the major R&D challenges. |
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