Proton driven plasma accelertion G. Xia Max-Planck-Institute for Physics July 15, 2011 LC Forum meeting, 14-15 July, Munich

LC Forum meeting, 14-15 July, Munich Outline Energy frontier machines Plasma wakefield acceleration-PWFA Proton-driven PWFA Summary LC Forum meeting, 14-15 July, Munich

Energy frontier machines Energy frontier machines (terascale or 1012 eV in beam energy) will help us unlock many secrets of our Universe, however, the machine size reach our limit (tens of kilometers), price tag is extremely high (billion dollars) How to make the life easier? LC Forum meeting, 14-15 July, Munich

LC Forum meeting, 14-15 July, Munich Motivation With an increase of beam energy, the size and cost of modern high energy particle accelerators reach the limit Plasma can sustain very large electric fields, a few orders of magnitude higher than the fields in metallic structures The plasma accelerators (laser driven-LWFA or beam driven-PWFA) developed rapidly in last decade, 50-100GV/m accelerating gradients have been demonstrated in labs The novel plasma accelerators can potentially minimize the size and cost of future machines LC Forum meeting, 14-15 July, Munich

The New Livingston Plot LC Forum meeting, 14-15 July, Munich Joshi & Katsouleas Physics Today 2003

Plasma Wakefield Acceleration (PWFA) I) Generate homogeneous plasma channel Ionization of gas via: Laser Beam RF Gas Plasma II) Send dense electron beam towards plasma = ion = electron Beam density nb Gas density n0 LC Forum meeting, 14-15 July, Munich

LC Forum meeting, 14-15 July, Munich PWFA III) Excite plasma wakefields Electrons are expelled r z Ion channel Space charge force of beam ejects all plasma electrons promptly along radial trajectories Pure ion channel is left: Ion-focused regime, underdense plasma LC Forum meeting, 14-15 July, Munich

PWFA Space charge of drive beam displaces plasma electrons. Electron motion solved with ... Space charge of drive beam displaces plasma electrons. driving force: Space charge oscillations (Harmonic oscillator) Plasma ions exert restoring force restoring force: Longitudinal fields can accelerate and decelerate! Plasma “structures” are also super-strong “quadrupoles”! (many thousands to Mega Tesla/m) Approximately mm-wave length! LC Forum meeting, 14-15 July, Munich

LC Forum meeting, 14-15 July, Munich Proton-driven PWFA p+ e- Drive beam: p+ E=1 TeV, Np=1011 σr=0.43 mm, σθ=0.03 mrad, σz=100 μm, ΔE/E=10% 600 GeV e- beam Witness beam: e- E0=10 GeV, Ne=1.5x1010 ≤1% ΔE/E in ~500 plasma Plasma: Li+ np=6x1014cm-3 External magnetic field: Field gradient: 1000 T/m Magnet length: 0.7 m LC Forum meeting, 14-15 July, Munich A. Caldwell et al, Nature Physics 5, 363 (2009).

LC Forum meeting, 14-15 July, Munich Simulation results Energy gain energy change energy spread LC Forum meeting, 14-15 July, Munich A. Caldwell et al., Nature Physics 5, 363 (2009).

LC Forum meeting, 14-15 July, Munich PWFA vs. PDPWA Pros. of PWFA Plasma electrons are expelled by space charge of beam, a nice bubble will be formed for beam acceleration and focusing. The short electron beam is relatively easy to have (bunch compression). Wakefield phase slippage is not a problem. Cons. of PWFA One stage energy gain is limited by transformer ratio, therefore maximum electron energy is about 100 GeV using SLC beam. Easy to be subject to the head erosion due to small mass of electrons Pros. of PDPWA Very high energy proton beam are available today, the energy stored at SPS, LHC, Tevatron SPS (450 GeV, 1.3e11 p/bunch) ~ 10 kJ LHC (1 TeV, 1.15e11 p/bunch) ~ 20 kJ LHC (7 TeV, 1.15e11 p/bunch) ~ 140 kJ SLC (50 GeV, 2e10 e-/bunch) ~ 0.1 kJ Cons. of PDPWA Flow-in regime responds a relatively low field vs. blow-out regime. Long proton bunches (tens centimeters), bunch compression is difficult. Wave phase slippage for heavy mass proton beam (small γ factor), especially for a very long plasma channel blow-out (p+) flow-in linear response nonlinear response LC Forum meeting, 14-15 July, Munich G. Xia, Talk given at PAC11 meeting in New York

LC Forum meeting, 14-15 July, Munich Short proton driver A magnetic chicane for bunch compression 4 km bunch compressor is required for 1 TeV p+ beam! LC Forum meeting, 14-15 July, Munich G. Xia, A. Caldwell et al., Proceedings of PAC09 (FR5RFP011) F.Zimmermann, G. Xia et al., Proceedings of PAC09, (FR5RFP004)

LC Forum meeting, 14-15 July, Munich Short bunch driver Self-modulation via plasma wakefield (the transverse instability modulates the long bunch into many ultra short beamlets at plasma wakelength. density modulation effect SPS beam at 5m Plasma @ 1e14 cm-3 on-axis (X = 0) beam density profile after 5 m propagation in plasma G. Xia, et al., AIP Proceedings of Advanced Accelerators Concepts 2010, 510-515. LC Forum meeting, 14-15 July, Munich A. Caldwell, K. Lotov, A. Pukhov, G. Xia, Plasma Phys. Control. Fusion 53, (2011) 014003.

Demonstration experiment at CERN PDPWA has the potential to accelerate electron beam to the TeV scale in a single stage. As a first step, we would like to demonstrate the scaling laws of PDPWA in an experiment with an existing beam kick-off meeting-PPA09 held at CERN in December 2009 A spare SPS tunnel is available for demonstration experiment With no bunch compression in the beginning old beam lines Kick-off meeting 2009 beam dump http://indico.cern.ch/conferenceDisplay.py?confId=74552 http://cerncourier.com/cws/article/cern/41714 beam line layout LC Forum meeting, 14-15 July, Munich G. Xia et al, Proceedings of PAC11 (TUOBN5), New York, 2011

Demonstration experiment at CERN Scientific Goal of Experiments: Initial goal is to observe the energy gain of 1 GeV in 5 m plasma. A plan for reaching 100 GeV within 100 m plasma will be developed based on the initial round of experiments Experimental Setup: Expected Results: A long SPS beam (uncompression) will be used in the first experiment. a self-modulation of the beam due to the transverse instability will produce many ultrashort beam slices at plasma wavelength. The modulation could resonantly drives wakefield in hundreds MeV/m with CERN SPS beam. Simulation shows that at optimum beam and plasma parameters, ≥ 1 GV/m field can be achieved. LC Forum meeting, 14-15 July, Munich G. Xia et al, Proceedings of PAC11 (TUOBN5), New York, 2011

Electron acceleration Plasma density in use: 7x1014 cm-3 SPS-LHC SPS-Opt. Beam energy [GeV] 450 Bunch population [1011] 1.15 3.0 Beam radius [μm] 200 Angular spread [mrad] 0.04 Normalized emittance [μm] 3.5 Bunch length [cm] 12 12.4 Energy spread [%] 0.03 LC Forum meeting, 14-15 July, Munich G. Xia et al, Proceedings of PAC11 (TUOBN5), New York, 2011

Plasma density variation 6 TeV electron beam can be achieved based on LHC beam, the wakefield gradient approaching 1 GV/m ! Increasing the plasma density properly at the moment of developed instability, the wave shift with respect to the main body of the beam will be stopped and one can obtain a stable bunch train that propagates in plasma for a long distance LC Forum meeting, 14-15 July, Munich A. Caldwell, K. Lotov, arXiv: 1105.1292v1 (2011)

LC Forum meeting, 14-15 July, Munich CERN’s interest PDPWA collaboration: Several workshops, biweekly phone meeting, and site visit at CERN Sumbitted the LoI two weeks ago to CERN Proposal defense at 102 SPSC meeting on June 28, 2011 Steve Myers CERN Director of Accelerators & Technology "CERN is very interested in following and participating in novel acceleration techniques, and has as a first step agreed to make protons available for the study of proton-driven plasma wakefield acceleration." LC Forum meeting, 14-15 July, Munich

LC Forum meeting, 14-15 July, Munich Summary Simulation shows that proton-driven plasma wakefield acceleration holds promise to accelerate the electron bunch to energy frontier in a single passage of plasma cell. Short and high energy proton bunch could be produced via conventional magnetic bunch compression or combined other compression schemes. Demonstration experiment on PDPWA is planning as a future project Further investigations are ongoing on the key issues such as accelerating positron beam, high repetition rate for high luminosity, beam instabilities, mobile ions, etc. LC Forum meeting, 14-15 July, Munich

Thanks for your attention ! LC Forum meeting, 14-15 July, Munich