Protondriven plasma wakefield acceleration in hollow plasma Yangmei

Proton-driven plasma wakefield acceleration in hollow plasma Yangmei Li Supervisor: Guoxing Xia 2016/12/13 Christmas meeting 1

Beam driven plasma wakefield acceleration Positively charged driver Uniform plasma r z • Electron driven: strong, radially linear focusing • Positron/Proton driven: radially nonlinear and longitudinally varying focusing force 2016/12/13 Christmas meeting 2

0. 62 Te. V e- beam energy frontier! • SPS (450 Ge. V, 1. 3 e 11 p/bunch) • LHC (7 Te. V, 1. 15 e 11 p/bunch) ~ 10 k. J ~ 140 k. J • SLAC (50 Ge. V, 2 e 10 e/bunch) ~ 0. 16 k. J • ILC (250 Ge. V, 2 e 10 e/bunch) ~ 0. 8 k. J • CLARA (250 Me. V, 1. 56 e 9 e-/bunch ) ~0. 06 Proton-driven plasma-wakefiled acceleration. A. Caldwell et al. , Nature Phys. 5, 363 (2009). 2016/12/13 Christmas meeting 3

The concept • Hollow plasma channel for electron acceleration • Create a regime completely without transverse plasma wakefields • Conservation of the norm. emittance of the witness beam Electron bunch Proton bunch rc r x=z-ct plasma electron density distribution 2016/12/13 Christmas meeting 4

Parameters for simulation Quasi-static PIC code: LCODE[1] • As there is no plasma focusing in the channel, quadrupoles now guide both the driver and the witness bunch. [1] Lotov, K. Phys. Rev. ST Accel. Beams 6, 061301 (2003). Plasma density, np 5 1014 cm-3 Hollow radius, rc Quadrupole period, Lq 0. 35 mm Population, Np Quadrupole strength, S 0. 9 m Energy, W 500 T/m Energy spread, Bunch length, σz Beam radius, σr δW/W Proton bunch 1. 15 1011 1 Te. V 10% 150 μm 350 μm Electron bunch 1. 0 1010 10 Ge. V 1% 15 μm 10 μm 2016/12/13 Christmas meeting 5

Simulation results on-axis acc field Radial variations of the transverse fields 2 D transverse plasma fields Mean energy and energy spread of the WB 2016/12/13 Christmas meeting 0. 62 Te. V 4. 6% 6

1. Normalized emittance Evolution of the transverse field at the midplane of the WB Initial value: 2. 0 mm mrad 2. 4 mm mrad Norm. emittance of the WB within 3σr 2016/12/13 Christmas meeting 7

2. Betatron radiation 2016/12/13 Tracking particles initially at four different radii Christmas meeting 8

3. Beam loading effect • Significantly mitigated beam loading effect • Well-preserved norm. emmitance • Reduce energy spread via extension of the bunch length or tailoring the bunch shape On-axis fields loaded with different charges of WB below 2. 5 mm mrad Mean energy and energy spread for different loaded witness beams 2016/12/13 Norm. emittance of the WB within 3σr for different loaded witness beams Christmas meeting 9

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