WG4: (Particle) Beamdriven. Summary. Sergey Antipov and Sebastien Corde

Transcription

1 WG4: (Particle) Beamdriven Acceleration Summary Sergey Antipov and Sebastien Corde

2 35 talks (+ discussions) and 13 posters Plasma (Sebastien Corde) Experimental progress Projects and simulations Plasma sources and PWFA diagnostics Injection methods Structures (Sergey Antipov) Dielectric loaded structures All-metal structures Bunch profiling, Transformer ratio, BBU control, efficiency

3 V. Dolgashev S. Antipov Beam driven structures

4 2 GV/m No breakdown 15 cm long structure (some indication of BBU) Presented by B. O Shea (UCLA) FACET High power high energy THz (tens of mj, sub GW peak power, 1% bandwidth)

5 Rf Breakdown Tests of Metal 100 GHz Structures (E204) Adjustable gap Current monitor FACET Two-halves structures Standing wave, travelling wave, stainless steel, copper Presented by V. Dolgashev (SLAC) breakdown signatures rf breakdowns 3.2 nc, gap 0.5mm Parameter Value Gap (2a) 0.5 mm Synchronous frequency 130 GHz Phase-per-cell deg RF 3.2 nc MW Acc. 3.2 nc 1.1 GV/m E 3.2 nc 3 GV/m H 3.2 nc 5.5 MA/m v g /c 3.5 % Att. Length 3.6 mm Att. Length/v g 0.34 ns Q value 277

6 Rf Breakdown Tests of Metal 100 GHz Structures (E204) Input coupler, cells 1-7, no damage Cells 16-23, fist signs of Iris 19-20, fist signs of damage damage From SEM inspection, we estimate following no damage pulse parameters Presented by V. Dolgashev (SLAC) Parameter Standing wave, copper Traveling Wave, Copper Traveling Wave, Stainless Steel Output coupler: massive damage. Cells , breakdown damage Acc. Gradient >0.16 GV/m 5.5 GV/m 1.1 GV/m E max >0.64 GV/m 11.4 GV/m 3 GV/m Pulse length ~3 ns ~2.3 ns 0.34 ns

7 High Power RF Generation at W-band Based on Wakefield Excited by Electron Bunch Train Dan Wang, W. Gai, J. Power, C. Jing, S. Antipov, J. Qiu, Goal High power High-frequency RF at W- band : Frequency ~ 91 GHz Peak Power ~ 100 MW Peak field ~ 300 MV/m Pulse duration 3.4 ~ 27 ns High harmonic radiation: 70 th x1.3 AWA (75 MeV / 5 nc x 32 bunches) Experimental setup Simulation result RF peak power : = 4.2 [MW] RF peak power : = 69.6 [MW] Ez (z=l) (MV/m) Ez (z=l) (MV/m) time (ns) ns s 3.1ns f 2.6ns d 3.1ns r E 80 MV / m Q 5nC 0.53mm single bunch time (ns) z as E 325 MV / m as Q 5nC per bunch 0.53 mm 8 bunches. z Measurement method Presented by D. Wang (ANL)

8 Measurements of ~460 GHz signal generation in a Metallic, Corrugated Beam Pipe ID=2mm L=5 cm period230um, groove 60um f = 459 GHz BW ~ 12% pulse ~ 20ps ATF beam: 50pC, σ z =60um (rms) E thz =1uJ (pulse) P peak = 50kW Interferometer measurement 459 ± 32 GHz energy spectrometer data Presented by S. Antipov (Euclid / ANL) ATF (BNL)

9 2 x 109 single bunch vs bunch train wake amplitude, V/m z, cm Bunch trains for wakefield generation

10 Commissioning of the Upgraded Argonne Wakefield Accelerator Facility (AWA) Manoel Conde (for the AWA Group) Following this week s approval of the required safety documentation the commissioning of the AWA facility will enter its final phase, bringing the drive beam energy up to 75 MeV. measured The new drive beam will enable the generation of high gradient wakefields (hundreds of MV/m) and the demonstration of significant acceleration of the witness beam (~ 100 MeV). Presented by M. Conde (ANL) Demonstration of staging for two-beam acceleration is planned for the near future AWA

11 High power beam-based THz source ATF (0.8nC / 2.4mm) 6 MW peak, 0.7THz, 160ps pulse, 1%BW, 1.4mJ pulse AWA (20nC / 6.3mm) 0.5 GW peak, 0.3THz, 320ps pulse, 1%BW, 155mJ pulse Stage I Stage II Stage III S. Antipov, C. Jing et. al. Phys. Rev. Lett. 108, (2012) Energy modulation via self-wakefield D. Xiang et. al PRL. 108, (2012) S. Antipov, et. al., PRL. 111, (2013) Chicane energy modulation conversion to bunch train G. Andonian et. al. Appl. Phys. Lett. 98, (2011) THz radiation wakefield structure TH z 500GHz signal, measured 2.5% BW 290 ps long pulse ~ 0.7% BW (theory) 40 MV/m; 350 kw peak power 58 uj Energy / pulse Narrow band signal Interferometer measurement Mirror position, mm ATF Bunch train in multimode Measured beam spectrum Energy chirped rectangular beam Measured beam spectrum Energy modulation Tunable 100% source: Range: THz Pulse bandwidth: 1% Energy in pulse: ~ mj Bunch train spectrum FFT measured x = mm 1.15 THz Presented by S. Antipov (Euclid / ANL) (mm)

12 Preliminary study on shaped electron bunch trains for PWFA at TUB Lixin Yan*, Xinlu Xu, Zhen Zhang, Dan Wang, Lujia Niu, Yingchao Du, Jianfei Hua, Jiaru Shi, Chih-hao Pai, Wei Lu, Wenhui huang, Huaibi Chen, Chuanxiang Tang Tsinghua University, Beijing, PRC The scheme for high peak current bunch train production: Bunch train is based on nonlinear longitudinal space charge oscillation*; The UV drive laser is produced by pulse stacking with birefringent crystals; Beamlet spacing in the bunch train can be tuned by the chicane. * P. Musumeci, et al. PRST-AB 16, (2013) Form factor and current distribution for 8-bunch with different chicane strength (left is for 70Gauss), the repetition rate can be tuned from 1.5THz to 3.2 THz here. We propose a scheme to directly measure the longitudinal E field structure in a low density PWFA: hybrid compression beam production high peak current beam with low current long tail A hybrid compression beam (~80MeV) with high current head(~9ka) and low current long tail is used to drive the wake and sample the acceleration gradient in a low density plasma(~1016cm-3); After exiting the wake, the energy change has a dependence on the longitudinal position within the beam which represents the acceleration gradient in the wake; With a deflecting cavity and a dipole installed after the plasma, one can temporally measure the energy of the modulated tail, thus realize the measurement of longitudinal electric field in the wake. Presented by L. Yan (Tsinghua)

13 A Beam Based Undulator C. Jing, S.Baturin, A.Kanareykin, P. Schoessow, A.Zholents. Proceedings IPAC 14, p S.Tantawi et. al. Phys. Rev. Lett. 112, (2014) Relative Amplitude Simulated Electric Field Undulator Mechanical Structure Electric Field Distribution Simulated Magnetic Field c B Distance Along the Undulator Axes cm a train of 4 75 MeV bunches of 25 nc each. Structure parameters are: a=375 um, c= 2.1 mm, d=2.85 mm ; dielectric permittivity of the inner tube ε=35.7 and of the outer layer ε= 5.7. λ u =2.9 mm, B u =24kG K=1.1 Presented by A. Kanareykin (Euclid)

14 Radiation of a Wakefield Excited by an Electron Bunch Train in a Section of Dielectric Waveguide Bunch train periodicity: 2.8 GHz Experimental data Measurement KIP T Simulation Presented by G. Sotnikov (KIPT)

15 Beam shaping, self wakes

16 Ramped Bunch shaping using self-wakefields Gerard Andonian Phase Space after DWS and chicane Enhanced TR, Constant decelerating E z Passive, compact Many design knobs Upcoming experiment at BNL ATF

17 Transformer Alternative Shape for Enhanced Transformer Ratios in Beam Driven Techniques Alternative shape: Sin- Ramp (blue) generates flat decelerating field (red). New proposed shaping techniques: (1) With DLW (2) Shaped laser pulse onto photocathode F. Lemery, P. Piot y = x N Wavelengths Presented by F. Lemery (NIU)

18 Transformer ratio measurement at ATF Beam profile after the mask in a dogleg Small witness beam: spectrometer Capillary OUT Drive (77 pc) and witness (3.5 pc) Theoretical: 4.5 Measured: 3.5 *preliminary data Drive beam head Capillary IN 130 kev energy gain (2.6 MV/m) E, MeV Drive head energy loss (21keV) Presented by S. Antipov (Euclid / ANL) Drive beam current E, kev

19 Beam self-wake applications and theory 200um 2mm Chirp corrector experiment at ATF L E (0) ds 2 q V n 4 Nz ( z Vt) x x y y S V 0 0 S. Antipov, et.al. Phys. Rev. Lett. 112, (2014) Presented by A. Kanareykin (Euclid) c Zc 0 2 a 2 c c 2Z c 2 (1 3 r0 / ac ) a 0 4 c p Zc ac 16 sq Zc ac

20 Towards practical designs High gradient breakdown Multipactor Charging BBU control

21 Multipactor control Multipactor turn on Multipactor turn off Solenoid over externally powered dielectric loaded structure to mitigate multipactor Presented by A. Kanareykin (Euclid)

22 BBU control 80% drive beam utilization Presented by C. Jing (Euclid / ANL) Single stage

23 Multi-meter collinear wakefield acceleration Use of FODO lattice for beam confinement BNS damping, i.e., use of drive beam energy chirp to desynchronize transverse particle oscillations and thus reduce the resultant transverse electric wakefield. Placing main bunch on the second maximum of the accelerating gradient with adaptive tapering of the dielectric tube to accommodate for the wakefield phase drift caused by particles lag in the drive bunch. current wake Use of higher energy drive beam. Adding a parabolic drive current component to increase energy chirp of the drive bunch through its wakefield if the initial chirp is too small. growth of chirp Presented by D. Schegolkov (LANL)

24 Sustained collinear wakefield acceleration Initial energy: 400 MeV. Dielectric tube inside/outside diameters: 2 mm / mm. Dielectric constant/main mode frequency: 3.75 / 300 GHz. FODO lattice initial quadrupole magnetic gradient: 1300 T/m. Drive bunch charge/length/chirp: 8 nc / 1 mm / 15%. Propagation distance: 20 m. Collaboration: Euclid Techlabs (C. Jing), AWA (J. Power), LANL (J. Simakov, D. Schegolokov), APS (A. Zholents) Drive bunch particle/energy loss: 0% / 80%. Witness bunch final energy: 2.03 GeV. Still working to improve the performance Presented by D. Schegolkov (LANL)

25 Summary New structures, new experiments: gradients, THz radiation Corrugated metallic ( GHz) Capillaries ( THz) Bunch train production and utilization in experiment Beam shaping (trending now) Efforts towards practical (multi-meter) design: FODO lattice over wakefield structures BNS damping for BBU control

26 Plasma Wakefield Acceleration: - Electron PWFA in the blowout regime - Self-modulated PWFA - Injection Methods in PWFA - Positron PWFA - Plasma sources and PWFA diagnostics - PWFA projects

27 Electron PWFA in the blowout regime

28 High Efficiency, High Gradient PWFA at FACET Mike Litos 70 pc accelerated Spectrally dispersed final beam Mean energy gain: 1.7 GeV Mean energy spread ~2% Gradient of ~5 GeV/m Mean wake-to-bunch energy transfer efficiency 18%

29 Energy (GeV) High Efficiency, High Gradient PWFA at FACET Mike Litos 100 Shots ordered by drivewitness bunch separation GeV 2014: increased plasma length from 30 cm to 130 cm Increased energy gain of ~6 GeV smaller separation

30 The Energy ratio of / can give us an estimate of the unloaded transformer ratio T from data! E deaccel 0.4 E accel 1.6 T = E accel / E deaccel ~ (38-20)/(20-13)~2.5 µ x = z - ct Using ionization injection, it s possible to increase this since witness bunch resides at E max

31 Transverse effects in PWFA Erik Adli We investigates transverse effects and instabilities at FACET by studying the effect of beam tilts and offsets. Experiment Observations : Apparent increase of wiggle amplitude with energy is consistent with expected image plane magnification (m12 term). No evidence of strong exponential growth. Strong indication of hosing suppressing. x ( mm) Simulation Results can be reproduced with good accuracy, using QuickPIC + Elegant simulations of offset witness bunch.

32 Plasma Ion Motion In Nonlinear PW FA Weiming An, Chan Joshi, Warren Mori (UCLA), Wei Lu (TUB) Simulation Using QuickPIC: Big challenge for simulating accelerated beam with ~100 nm spot size In Li + Plasma Δ 25 nm 00 µm x 400 µm x 300 µm Box 6384 x x 2048 Cells Δ 3 nm 12 µm x 12 µm x 60 µm Box 4096 x 4096 x 512 Cells The beam emittance growth is in a manageable scale when the accelerated beam is matched to the 1/2 focusing force initially. A typical trailing beam only has an emittance growth of 20% The final emittance for a round beam is proportional to the phase space action of the beam particle (σ r0, p 0 = 0), which not only depends on the peak ion density but also the width of the ion collapse. W hen the beam has asymmetric emittance, in one direction the emittance barely grows and in the other direction the emittance growth is still small.

33 Self-modulated PWFA

34 Patric Muggli Max Planck Institute for Physics Munich P. Muggli P. Muggli, AAC 14 07/2014 First Experimental Results of E209 at SLAC FACET: Self-modulation Instability of a Long Electron Bunch in a Dense Plasma?

35 SMI EVIDENCE? Energy Loss Focusing/defocusing/halo CTR Interferometry Modulation L beam /λ pe 2 e - beam: E=20.35GeV N e- =1.9x10 10 r =40µm L~500µm FWHM Plasma (E200): L~1.3m n e =8X10 16 cm -3 => pe =115µm Three indications of SMI occurrence?

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37 Injection Methods in PWFA

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40 Summary E217 Ionization Injection Experiment at FACET - Ionization injection is used to separate injection and acceleration in a PWFA. Ionization injection can be used to separate injection and acceleration stages in a PWFA - He electrons was accelerated by a loaded gradient of ~30 GeV/m. The upstream plasma ramp of a Li plasma was used as an injection site for He electrons He electron beam accelerated by a loaded accelerating gradient of ~30 GeV/m have been observed These electrons have much lower divergence than the main beam electrons Scaling of observed electron energies is consistent with injection of He electrons in the plasma up-ramp Pre-ionization with Laser ionization removes the He electrons from the ramp, and only main beam electrons are observed Simulation corroborates observed features of accelerated electrons - These electrons have much lower divergence and emittance than the main beam electrons. - Pre-ionization of He with laser suppresses injection. - Simulations corroborated observed features of accelerated electrons. 6

41 P. Muggli AAC /2014 Acceleration of a LWFA Electron Bunch In a Proton-driven PWFA Patric Muggli Max Planck Institute for Physics, Munich muggli@mpp.mpg.de

42 LWFA e - INJECTION INTO p + -PWFA Beam requirements: < pe /10 or ~ 0.4ps High charge ~1nC High current ~2.4kA Synchronized with wakefields (i.e., ionization laser) Injection between closely-spaced plasmas Compact Explore the possibility of using LWFA e - bunch Interesting simulation challenge: LWFA -> PWFA P. Muggli AAC /2014

43 Tunable multibunch train production with underdense photocathode PWFA Bernhard Hidding et al. LAOLA. Trojan Horse, PRL Use of multiple photocathode release lasers allows multibunch trains, where each bunchlet is independently tunable. - Extreme flexibility allows Advanced Electron Beam Synthesis. - Paves way for most exotic configurations, e.g. spatially overlapping fs high brightness bunches with different colors to drive multi-color light source.

44 Attosecond electron bunches from underdense plasma photocathodes by simultaneous space-time focused lasers Bernhard Hidding et al. LAOLA. - Quality and duration of Trojan Horse beams are limited by the Rayleigh length of the photocathode laser. - Simultaneous space-time focusing allows a dramatical reduction of the axial region where the laser has high peak intensity, by having the different colors of the laser overlap only at the focus. - Emittance and brightness substantially improved compared to normal Trojan Horse (brightness up to A.m -2.rad -2 that s 6 orders of magnitude brighter than LCLS).

45 Plasma torch electron injection in plasma wakefield accelerators * Plasma Torch: laser ignites a plasma column in the pathway of a plasma wake Considering 3 cases: Phase space of H, and He electrons. Calculating properties for electrons above the threshold. 192 MeV 0 MeV 116 MeV 0 MeV 60 MeV a) 100 MeV b) 20 MeV c) 20 MeV 0 MeV at 5mm acc. length neutral H, density: 4e18 / cm³ emittance charge mean energy energy spread peak current 5.3 mm mrad 36 pc MeV 13.2 % 2.5 ka neutral H, density: 4e18 / cm³ neutral He, density: 3e18 / cm³ emittance charge mean energy energy spread peak current 12 mm mrad 0.3 nc 100 MeV 10.9 % 11.5 ka pre-ionized H, density: 5e17 / cm³ neutral He, density: 1e18 / cm³ a) torch laser ionizes only LIT gas b) torch laser ionizes HIT as well as LIT c) torch laser ionizes HIT in pre-ionized LIT. emittance charge mean energy energy spread peak current 2.5 mm mrad 2.3 nc 46.3 MeV 23.2 % 21 ka * to be published Summarizing: Choosing ~1ps delay between torch laser and driver beam leaves no time for hydrodynamic expansion. Creating sharp plasma density transitions that are capable of trapping high current and charge witness bunches, with good emittances and bad energy spread. torch laser Ti:Sa ; ~1ps before driver at 0.4 mm a 0 = w 0 = 35 µm at 0.4 mm a 0 = 0.03 w 0 = 30 µm at 0.8 mm a 0 = w 0 = 100 µm

46 Trapping in a RISING density Phase-mixing (a)$ p$! (b)$ p$! No trapping in bucket # 1 Injection in multiple buckets " " " beam*excited$electron$ beam*excited$electron$ (c)$ trapping in bucket # 1 p$! (d)$ p$! laser*excited$electron$ laser*excited$electron$

47 Positron PWFA

48 Slide from 2012 WG4 summary There%is%no%clear%path%to%accelerate%e + %bunches%in%the%pwfa!%

49 Hollow Channel PWFA at FACET Spencer Gessner Hollow channels provide a method to accelerate beams in a plasma without transverse forces from background ions. We use a special binary optic to create a hollow laser beam, which we use to ionize an annulus of plasma. The first hollow channel experiment studied the transverse effects of a hollow channel plasma on a positron beam. J 8 Mask Channel Raster Scan J 8 Profile Deflection vs. Position

50 High-gradient positron-driven plasma wakes at FACET Sebastien Corde - First experimental generation of high-gradient positron wakes. - Simultaneous acceleration of two species: e+ and e-. - Demonstrated electron injection in a positron-wake, with threshold at positrons. - Multi-GeV scale acceleration. Positrons Electrons

51 Positron plasma wakefield acceleration in a self-driven hollow channel Novel configuration of e+ PWFA generates hollow channel Tightly focused e + beam propagating in homogeneous plasma: e + beams repel the plasma ions in its passage If the beam density is high the ion motion is not negligible As the electrons follow the ions a hollow channel is formed 3D OSIRS simulation showed e + driven hollow channel e+ tightly focused drive beam Plasma hydrogen ions (protons) Features of this hollow channel Transverse wakefields are low and mainly focusing for e + s Accelerating wakefields on the order of cold wave-breaking field - in non linear regime (sow-tooth shape) 3D simulations showed witness positron bunch acceleration Propagation direction Onset of hollow channel formation can be reached with at SLAC/FACET Hollow plasma channel (also with no neutras) Test particle e+ witness bunch

52 Plasma Source and PWFA diagnostics

53 Laser Ionized Preformed Plasma at FACET Selina Green A 10-TW Ti:sapphire laser system has been successfully commissioned and operated at FACET since The use of an axicon lens was demonstrated to focus a laser that ionizes the alkali metal vapor to form a plasma column suitable for PWFA. Achieved accelerating gradient of ~5 GeV/m for a witness bunch The laser intensity is sufficient to ionize a hydrogen filled gas cell => H is an attractive choice for future PWFA experiments! The high power laser opens up numerous exciting possibilities for new experiments at FACET: Positrons and hollow channel plasmas Trojan Horse Plasma Wakefield Acceleration Self-modulation of long lepton bunches (σ z ~500μm) in a dense laser-ionized plasma THz radiation pump-probe measurements, utilizing both the high-field THz pulses from the e-beam and the laser at FACET

54 Erdem Öz,Fabian Batsch,Patric Muggli, MAX PLANCK INSTITUTE FOR PHYSICS,MUNICH, GERMANY AAC 2014 Laser Ionized Rb Vapor Plasma Source Self modulation introduces a strict requirement on plasma density uniformity for injected electrons to stay in accelerating focusing phase, Dn n 0.2% Field Ionized Rubidium Vapor Cell with Oil Heating and Fast Valves Satisfies This Condition* Dn n = DT T Rb (4.177 ev) is chosen because of low laser intensity (I=1.7x10 12 Wcm -2 ) required to tunnel ionize and low temperature requirement ( o C) to reach cm % ionization Plasma density = Vapor Density (n) Plasma density uniformity = Vapor Density uniformity FAST VALVE DESIGN REQUIREMENTS Opening Time Closing Time Environment Temperature Leak Rate ~10 ms <1 s Rubidium, radiation resistant o C 1.75e-2 mbar liter/sec Requires a special heating system to provide Uniform K over 10 m, the first 3 m custom built prototype built by UK Grant s instruments satisfies the requirement Requires special fast valves to preserve uniformity during beam-plasma interaction, are developed by VAT to be delivered soon. Aperture Size (D) 4 cm Number of Cycles *Details: A novel Rb vapor plasma source for plasma wakefield accelerators, Nuclear Instruments and Methods in Physics Research Section A

55 Optical characterization of beam-driven plasma wake field accelerators 20 GeV e-bunch Probe angle about 0.01rad Lithium plasma oven 1.5m object plane Rafal Zgadzaj, Zhengyan Li, Michael C. Downer UT Austin (E-224) Spencer Gesner, Sebastien Corde, Mike Litos, Christine Clarke, Margaux Schmeltz, James Allen, Selina Green, Mark Hogan, Vitaly Yakimenko SLAC/FACET, Chan Joshi UCLA, Patric Muggli MPI (E-224 and E- 200) 20 GeV e-bunch Compressed 800nm pulse Plasma CCD object plane1 object plane2 CCD1 CCD2 CCD3 object plane3 FINAL SETUP imaging lens Probe imaging lens PRELIMINARY SETUP null Plasma evolution after e-beam ionization image Ionization Onset Laser produced plasma column at increasing laser energy. AAC 2014

56 PWFA Emittance and Beam Parameter Measurement Joel Frederico 1. Disperse, slice in energy 2. Find width of energy slices 3. Fit Linac Model 4. Extract Emittance, Twiss Stable Requires only quad magnet strength Does not assume imaging Recovers waist location Agnostic- applies to any beam separable in energy Experimentally measure emittance preservation in PWFA!

57 Projects

58 Target FLASHForward A beam-driven plasma wakefield accelerator to power FELs Future-oriented wakefield-accelerator research and development at FLASH > FLASHForward is a beam-line for novel accelerator research and development, experiments starting 2016 FLASH linac > beamline scheme Extraction 4 fs, 100 µj + 25 TW Probe/ionization lasers Beam matching and focussing section Differential pumping ar ea ~80 m Laser/plasma photon diagnostics TDS Driver dump Beam diagnostics section Undulator Witness dump X-ray diagnostics tunable R56 : > -2mm to 4mm > allows variable compression and high peak current (10kA) > novel types of witness-bunch generation for unprecedented PWFA beam quality > laser-triggered ionization injection > beam and wake-triggered ionization injection > density down-ramp injection > external injection (two pulses from photo gun) > FEL quality electron bunches with interesting properties > high-energy (1.6 to > 4 GeV) > low transverse emittance (~100 nm) > ultrashort (~ fs) > high peak current (> 1 ka) > lasing observed in 3D time-dependent Genesis simulations > experiments on demonstration of FEL-gain starting in 2018 LAOLA. Lucas Schaper plasma.desy.de AAC workshop WG4 16 March 2014 Page 00 Lucas Schaper Lucas.Schaper@DESY.de plasma.desy.de Thursday, 17 July 14

59 Update on the Experiment Patric Muggli Max Planck Institute for Physics, Munich for the AWAKE Collaboration P. Muggli AAC /2014

60 Change of injection scheme: from side injection to on-axis injection, simpler to implement Experiments planned for 2016 P. Muggli AAC /2014

61 Thank you for your attention