Temperature uniformity measurements and studies of bunch parameter variations for the Advanced Wakefield Experiment, AWAKE

• Main Author: Savard, Nicolas
• Other Authors: Merminga, Lia
• Language: English; en
• Published: 2016
• Subjects: plasma; wakefields; accelerator
• Online Access: http://hdl.handle.net/1828/7546

The Advanced Wakefield Experiment, or AWAKE, is an experiment based at CERN (European Organization for Nuclear Research) whose purpose is to demon- strate the acceleration of electrons using plasma wakefields driven by a charged par- ticle bunch. As a proof-of-principle experiment, AWAKE will be propagating a high- energy proton bunch through 10 meters of plasma to drive the wakefields for electron acceleration. To accelerate the electrons, we want to inject them into regions of both focusing and acceleration within these wakefields behind the proton bunch. In order for the electrons to stay within this optimal accelerating/focusing region, we need to maintain uniform plasma density within 0.2%, and we need to inject when the wakefield phase-velocity is constant. To preserve uniform plasma density, we use a liquid heat-exchanging pipe which can maintain stable temperatures, and therefore uniform rubidium vapor/plasma densities, to within 0.2%. We show that this is pos- sible using Galden HT270 as a heat-exchanging liquid. We also show that additional components required for this system will need external heating to prevent heat-loss, and therefore temperature non-uniformity. Furthermore, using the PIC simulation OSIRIS, we study how changing size parameters of the initial proton bunch by ±5% a ects the phase-velocity of the wakefield. It is seen that these parameter variations will not significantly affect the optimal region size and energy gain of injected elec- trons; so long as the electrons are injected at regions of ξ near σzb of the proton bunch and after 4 m of bunch propagation length in the plasma. === Graduate