Plasma acceleration experiments at PITZ Osip Lishilin Laplas-2018, - PowerPoint PPT Presentation

Plasma acceleration experiments at PITZ Osip Lishilin Laplas-2018, 2018-01-30, Moscow

PITZ facility

PITZ facility • Flexible photocathode laser system • Arbitrary longitudinal pulse shape • Up to 24 ps FWHM long, 2 ps fronts • Electron beam momentum up to 25 MeV/c after Booster • Electron beam charge up to 5 nC • Longitudinal phase space measurement employing a transverse deflecting cavity (TDS) and a dipole spectrometer. Temporal resolution up to 0.3 ps, momentum Free pulse shaping resolution up to 10 keV/c | Plasma acceleration experiments at PITZ | Osip Lishilin | 2018-01-31 Page 3

Beamline upgrades Quad 7…8 Dipole Quad 5…6 Plasma cell Quad 1…4 Electron Beam | Plasma acceleration experiments at PITZ | Osip Lishilin | 2018-01-31 Page 4

Plasma sources Lithium plasma cell Gas discharge plasma cell

Cross-shaped heat pipe oven plasma cell Thermal Heating Coils Design: 2 nd generation Insulation Gerald Koss Cooling Sleeve e - Electron Window Buffer Gas Distribution Gas loaded heat pipe principle Ionization Laser Path Ar Ar Li z 0 | Plasma acceleration experiments at PITZ | Osip Lishilin | 2018-01-31 Page 6

Heat pipe plasma cell: ionization laser and its transport • Coherent COMPexPro 201: ArF Excimer Laser, 193 nm, up to 400 mJ / pulse, 10 Hz > Side coupling advantage: Well defined and adjustable plasma channel length Optics  Option: Add filter to implement density ramps or other plasma box profiles | Plasma acceleration experiments at PITZ | Osip Lishilin | 2018-01-31 Page 7

Lithium plasma cell • Experimental run in 2016: suboptimal buffer gas pressure led to a low plasma density of  1.3x10 14 cm -3 and eventual condensation of lithium in the side arms • Upcoming run in 2018: • For the upcoming run heat pipe oven parameters are adjusted -> stable operation without condensation issues, measured vapor is density more than 10 16 cm -3 • Variable ionization channel length | Plasma acceleration experiments at PITZ | Osip Lishilin | 2018-01-31 Page 8

Gas discharge plasma cell > > ArH 2 gas at 0.1 – 10 mbar (sealed off) Plasma densities up to 5x10 15 cm -3 > > 10mm diameter, 100mm length Pre-ionisation via glow discharge discharge channel > 2-10µs pulses of 200 – 1000A | Plasma acceleration experiments at PITZ | Osip Lishilin | 2018-01-31 Page 9

PWFA experiments Self-modulation instability High Transformer ratio

EAAC Workshop 2013: Patric Muggli, AWAKE: A Proton-Driven Plasma Wakefield Experiment at CERN • Use high energy proton beams from SPS to drive plasma wave • Convert proton beam energy to accelerate electron beam in single stage > High accelerating gradient requires short bunches (  z less than 100µm) > Existing proton Caldwell et al., NIM A (2016) machines produce Caldwell et al., Nature Physics (2009): long bunches (10cm) 2 𝑂 0.6 𝐹 𝑨,𝑛𝑏𝑦 = 240(𝑁𝑊 𝑛 −1 ) Courtesy: 4𝑦10 10  𝑨 𝑛𝑛 Self-modulation! Patric Muggli, Erdem Öz | Plasma acceleration experiments at PITZ | Osip Lishilin | 2018-01-31 Page 11

Self-modulation instability (SMI) at PITZ Expected measured phase space at 10 15 cm -3 > Study the physics of the self modulation instability > Self-amplified transverse modulation of bunch and coherent wake driving > Studies for proton driven plasma wakefield acceleration (AWAKE, CERN) | Plasma acceleration experiments at PITZ | Osip Lishilin | 2018-01-31 Page 12

SMI Experimental Results: 1) Time Resolved Beam 2016: Lithium plasma cell • The first direct time-resolved experimental observation of a self-modulated electron beam Q=970 pC Plasma density:  10 14 cm -3 | Plasma acceleration experiments at PITZ | Osip Lishilin | 2018-01-31 Page 13

SMI Experimental Results: 2) Longitudinal Phase space 2016: Lithium plasma cell • Momentum modulation with 200 keV/c amplitude Q=970 pC Plasma density:  1.3x 10 14 cm -3 | Plasma acceleration experiments at PITZ | Osip Lishilin | 2018-01-31 Page 14

SMI Experimental Results 3): Self-Modulation vs plasma density 2016: Lithium plasma cell • Measured time resolved electron bunch for different delays of the electron bunch arrival time relative to the ionization laser pulse • Paper submitted to PRL | Plasma acceleration experiments at PITZ | Osip Lishilin | 2018-01-31 Page 15

SMI Experimental Results 4): Parameter scan at higher plasma densities 2017: Gas discharge plasma cell Experiment with higher plasma densities (up to  2x10 15 cm -3 ) • • 2-d parameter scan: main solenoid and charge • Some scans show more evident signs of self-modulation • Data is not fully analyzed yet Solenoid current: 380 A Solenoid current: 370 A | Plasma acceleration experiments at PITZ | Osip Lishilin | 2018-01-31 Page 16

High Transformer Ratio Collinear wakefield acceleration (linear theory): Fundamental theorem of beamloading: E acc /E dec < 2  Only true for symm. Bunches  Various E + proposed bunch shapes HTR: E - Head E + / E - > 2 | Plasma acceleration experiments at PITZ | Osip Lishilin | 2018-01-31 Page 17

HTR measurement method • Time resolved energy measurement (slice energy) on screen YAG screen for high charge driver  maximum loss in driver • LYSO screen for low charge witness  Increase of maximum energy of witness • | Plasma acceleration experiments at PITZ | Osip Lishilin | 2018-01-31 Page 18

HTR measurement • Measured High Transformer ratio up to ~5.3 • Stable only in low density plasma, <5x10 13 cm -3 • 508 pC driver, 10 pC witness • Paper is in preparation | Plasma acceleration experiments at PITZ | Osip Lishilin | 2018-01-31 Page 19

Laboratory Astrophysics • Bell‘s instability: Amplification of magnetic fields in a plasma, induced by cosmic rays • Idea: find parameter scaling so that astrophysical phenomena can be investigated in the laboratory, using PITZ beam and plasma source • Extensive simulation study is ongoing • Challenging, but no “show stoppers” found yet | Plasma acceleration experiments at PITZ | Osip Lishilin | 2018-01-31 Page 20

Conclusions • Two plasma sources are commissioned • First time resolved measurements of the Self-modulation instability • Advanced measurements in 2018 • Transformer ratio >5 is demonstrated • Investigations for lab astrophysics are ongoing | Plasma acceleration experiments at PITZ | Osip Lishilin | 2018-01-31 Page 21

Thank you for your attention! Plasma team @ PITZ: M. Gross, G. Loisch, O. Lishilin, G. Koss, S. Philipp, S. Maschmann Former members: G. Pathak, J. Engel, P. Weidemann, M. Schinkel, V. Wohlfarth, R. Schuetze | Plasma acceleration experiments at PITZ | Osip Lishilin | 2018-01-31 Page 22

| Plasma acceleration experiments at PITZ | Osip Lishilin | 2018-01-31 Page 23

Backup SMI based density measurements > Density calculation from SMI induced patterns in transverse / longit. phase space Fourier spectrum > Density measurement at exact point (& time) of bunch passage > Spectroscopic benchmark measurements under preparation > Simulations show errors <10% | Plasma acceleration experiments at PITZ | Osip Lishilin | 2018-01-31 Page 24

Backup HTR definition > No direct field measurement > No controlled injection of witness bunch (witnessing wide phase range) > Measuring & simulating “ effective Transformer Ratio“: E slice_max, witness, Plasma On – E slice_max, witness, Plasma Off max( E (mean-slice-energy), driver, Plasma Off – E (mean-slice-energy), driver, Plasma On ) > Worst case underestimating TR: highest energy witness electrons with plasma not necessarily at highest energy without plasma | Plasma acceleration experiments at PITZ | Osip Lishilin | 2018-01-31 Page 25

Backup Simulations (ASTRA and HiPACE) | Plasma acceleration experiments at PITZ | Osip Lishilin | 2018-01-31 Page 26