LAOLA. Plasma wakefield acceleration: towards high-quality stable beams at FLASHForward ‣‣ Julia Grebenyuk FLASHForward team: Alexander Aschikhin, Christopher Behrens, John Dale, Carlos Entrena, Lars Goldberg, Julia Grebenyuk, Bernhard Hidding, Tobias Kleinwächter, Alexander Knetsch, Olena Kononenko, Vladyslav Libov, Alberto Martinez de la Ossa, Jens Osterhoff, Timon Mehrling, Halil Tarik Olgun, Charlotte Palmer, Lucas Schaper, Jan-Patrick Schwinkendorf, Matthew Streeter, Bernhard Schmidt, Steffen Wunderlich, Johann Zemella Tuesday, February 18, 14 1
Outline Introduction to plasma acceleration FLASHForward ‣‣ General setup and schedule Physics programme Experimental setup Summary Tuesday, February 18, 14 2
LHC 4th July 2012 Announcement of the Higgs discovery Tuesday, February 18, 14 3
Livingston chart Tuesday, February 18, 14 4
Accelerators for applications Synchrotron light sources Free - electron lasers Particle therapy Tuesday, February 18, 14 5
Limitations Circular machines : limited by the magnetic field and synchrotron radiation Linear machines : limited by accelerating gradients in RF Gradient of 100 MV / m Limited by material breakdown Tuesday, February 18, 14 6
RF vs. plasma RF - Transfer of electromagnetic energy of the waves in vacuum to kinetic energy of particles Plasma acceleration - Transfer of electromagnetic energy of laser pulse or a beam to kinetic energy of particles via a medium : plasma Tuesday, February 18, 14 7
First idea of ‘collective’ acceleration 1956 Tuesday, February 18, 14 8
First idea of ‘collective’ acceleration 1956 Idea : accelerate ions by group of electrons moving in front of them Ions are heavy Tuesday, February 18, 14 9
Plasma acceleration Tajima and Dawson, 1979 > Induce large electric fields in plasma by a laser a0=1.8 > No material breaking 5 electron density n(x) − 1 scalar potential � (x) laser vector potential a(x) electric field e(x) 4 3 > Stable, high amplitude Norm. quantities 2 waves 1 0 > Phase velocity on the − 1 order of a speed of light − 2 − 30 − 25 − 20 − 15 − 10 − 5 0 5 x=k p � Tuesday, February 18, 14 10
Plasma acceleration The field gradient scales with plasma density p E 0 (V / m) ≈ 96 n e (cm − 3 ) Gradients up to 100 GeV / m Courtesy of T. Mehrling The size of the accelerating structure is plasma wavelength Tuesday, February 18, 14 11
1979 > 2006 Plasma density : 2 . 7 x 10 18 cm - 3 40 TW laser with 10 18 W cm - 2 Tuesday, February 18, 14 12
Plasma accelerators > Laser - driven accelerators > LWPA is limited by dephasing ( LWPA ) and pump depletion length, > Beam - driven accelerators which limits beam quality and ( PWFA ) energy gain > Plasma beat - wave > Self - modulation beam - driven > Laser e ffj ciency and stability are accelerators a challange Tuesday, February 18, 14 13
Plasma accelerators > Laser - driven accelerators > LWPA is limited by dephasing ( LWPA ) and pump depletion length, > Beam - driven accelerators which limits beam quality and ( PWFA ) energy gain > Plasma beat - wave > Self - modulation beam - driven > Laser e ffj ciency and stability are accelerators a challange Tuesday, February 18, 14 14
Beam-driven plasma acceleration Beam - driven plasma Courtesy of A. Martinez de la Ossa acceleration is based on similar principle Beam space - charge repels electrons and creates a wake Tuesday, February 18, 14 15
Beam-driven plasma acceleration Energy doubling of the 42 GeV SLAC beam Blumenfeld et al, Nature 445, 741 (2006) Tuesday, February 18, 14 16
Particle injection How to get the surfer on the wave? Tuesday, February 18, 14 17
Particle injection How to get the surfer on the wave? External injection > tailored well-characterised beam externally injected in plasma wake Tuesday, February 18, 14 18
Particle injection How to get the surfer on the wave? External injection Internal injection > tailored well-characterised beam > injecting and accelerating externally injected in plasma wake background plasma particle Wave - breaking Controlled : > ionisation - induced > colliding laser - pulses > density transitions > magnetic - field induced Tuesday, February 18, 14 19
External injection Challenges : > Requires short bunches > Synchronisation > Matching, emittance conservation T. Mehrling et al, Phys. Rev. ST Accel. Beams 15, 111303 (2012) Tuesday, February 18, 14 20
Wave breaking Self - injection of background plasma electrons to the wake when some particles outrun the wake Process is di ffj cult to control Final bunch quality depends strongly of the mechanism of population of 6D phase-space > control of injection is crutial Tuesday, February 18, 14 21
Transformer ratio Energy transfer from the R = E acc driver to the witness beam E decel In standard PWFA setups E acc - maximum of the accelerating field of the transformer ratios are < 2 witness beam For ramped - current beams E decel - maximum of the decelerating field of the transformer - rations are drive beam predicted to be very high (> 5 ) K. V. Lotov. Efficient operating mode of the plasma wakefield accelerator. Physics of Plasmas, 12:053105, May 2005. Tuesday, February 18, 14 22
LAOLA at DESY LAOLA , the La boratory f o r L aser- and beam-driven plasma A cceleration is a collaboration between groups from DESY and the University of Hamburg. http://laola.desy.de Tuesday, February 18, 14 23
Plasma acceleration at DESY Courtesy of J. Osterhoff Tuesday, February 18, 14 24
FLASHForward Courtesy of J. Osterhoff Tuesday, February 18, 14 25
� � DESY and FLASH > FLASH : linear accelerator 2.3 km using super-conducting 6.4 km ↑ 300 m RF structures > Primary role: drive an FEL by high current, short, ↑ 3.4 km low emittance beams > Similar requirements for PWFA Tuesday, February 18, 14 26
FLASHForward scientific goals > Generate and accelerate beams in PWFA; 1 > Demonstrate high transformer ratios (> 2 ) from the driver to the witness . Tuesday, February 18, 14 27
FLASHForward scientific goals > Generate and accelerate beams in PWFA; 1 > Demonstrate high transformer ratios (> 2 ) from the driver to the witness . Explore controlled injection processes II > External Injection of a secondary bunch (second bunch generated by a second laser at the FLASH source); > Second bunch accelerated by wake generated by first; > Controlled internal injection (density transitions, ionisation-induced, Trojan horse). Tuesday, February 18, 14 28
FLASHForward scientific goals > Generate and accelerate beams in PWFA; 1 > Demonstrate high transformer ratios (> 2 ) from the driver to the witness . Explore controlled injection processes II > External Injection of a secondary bunch (second bunch generated by a second laser at the FLASH source); > Second bunch accelerated by wake generated by first; > Controlled internal injection (density transitions, ionisation-induced, Trojan horse). III Application of generated bunches > capture and transport of generated bunches to an undulator > FEL Tuesday, February 18, 14 29
FLASH beam FLASH Gaussian beam 20 to 500 fs longitudinal RMS 10 microns radial RMS Energy ~1.2 GeV, 0.1% energy spread 1 μ m transverse emittance, ~2.5 kA peak current Standard mode, can be used in parallel with main FLASH Tuesday, February 18, 14 30
FLASH beam FLASH Gaussian beam Piot et al., Phys. Rev. Lett. 108, 034801 (2012) 20 to 500 fs longitudinal RMS 10 microns radial RMS FLASH ‘triangular’ beam Energy ~1.2 GeV, 0.1% energy spread 60 to 200 fs length 1 μ m transverse emittance, Energy ~1.2 GeV, 0.1% energy ~2.5 kA peak current spread 1 μ m transverse emittance, ~2.5 kA peak current Standard mode, can be used in parallel with main FLASH Requires dedicated runtime Predicted high transformer ratios Tuesday, February 18, 14 31
FLASHForward Phase I (2015+) > FLASH2 beamline design and installation > PWFA experiments with controlled injection techniques sdasd sdasd sdasd Tuesday, February 18, 14 32
FLASHForward Phase II (2018+) Phase I (2015+) > PWFA-induced beams for > FLASH2 beamline design and applications installation > Installation on undulator and > PWFA experiments with corresponding diagnostics controlled injection techniques Tuesday, February 18, 14 33
Experimental setup > FLASH beam extraction and its transport to the interaction region; > The main interaction region (plasma cell inside the experimental chamber); > Post-plasma diagnostics to measure properties of the driver and witness bunches; > Witness beam extraction out of the plasma and transport to the undulators. Tuesday, February 18, 14 34
FLASHForward with gaussian driver Simulations by A. Martinez de la Ossa FLASH Gaussian beam 20 to 500 fs longitudinal RMS 10 microns radial RMS Energy ~1.2 GeV, 0.1% energy spread 1 μ m transverse emittance, ~2.5 kA peak current > Can be used in parallel with FLASH 1/2 operation > Transformer ratio of ~2 > Field gradients up to 17 GV / m > Doubling of FLASH beam energy within less than 10 cm > Most of the physics programme will be done in this mode Tuesday, February 18, 14 35
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