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Beam Plasma Physics Experiments at ORION

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  1. 2nd ORION Workshop February 18-20, 2003 Beam Plasma Physics Experimentsat ORION Mark Hogan SLAC

  2. 2nd ORION Workshop February 18-20, 2003 Outline • Large Fields Show Large Promise in Beam-Plasma Physics • Highlights of Recent Experiments • Example Experiments • Look towards the Working Group asking how some of the open • questions might be addressed at ORION

  3. Recent Results III: Promise and Challenge • E-157 & E-162 have observed a wide range of phenomena with both • electron and positron drive beams: Electron Beam Refraction at the Gas–Plasma Boundary e- & e+ Focusing X-ray Generation Wakefield acceleration qµ1/sinf q≈f o BPM Data – Model Phys. Rev. Lett. 2002, 2003 To Science 2003 Phys. Rev. Lett. 2002 Nature 2002 • ORION researchers over the past few years, developed a facility for doing unique physics, and also many of the techniques and the expertise necessary for conducting next experiments

  4. evolves to Concepts For Plasma-Based Accelerators Pioneered by J.M.Dawson Research into “advanced” technologies and concepts that could provide the next innovations needed by particle physics. In many cases one is applying or extending physics and technology that is its own discipline to acceleration (ex. plasma physics, laser physics…). Active community investigating high-frequency rf, two-beam accelerators, laser accelerators, and plasma accelerators. • Laser Wake Field Accelerator(LWFA) • A single short-pulse of photons • Plasma Beat Wave Accelerator(PBWA) • Two-frequencies, i.e., a train of pulses • Self Modulated Laser Wake Field Accelerator(SMLWFA) • Raman forward scattering instability • Plasma Wake Field Accelerator(PWFA) • A high energy electron (or positron) bunch

  5. But can it lead to…? A 100 GeV-on-100 GeV e-e+ ColliderBased on Plasma Afterburners 3 km 30 m Afterburners LENSES 50 GeV e- 50 GeV e+ e-WFA e+WFA IP

  6. Many Issues Need to Be Addressed First 1. Development of plasma sources capable of producing densities > 1016 e-/cm3 over distances of several meters. 2. Quantify limitations of plasma lenses due to chromatic and spherical aberrations. 3. Stable propagation through such a long high-density ion column – beam matching and no limits due to electron hose instability. 4. Preservation of beam emittance 5. Accelerating gradients orders of magnitude larger than those studied to date – via shorter bunches and optimized profiles. 6. Beam loading of the plasma wake with ~ 50% charge of the drive beam In fact, these issues will need to be addressed for many applications of beam plasma interactions Many advances in recent years…

  7. E-150: Plasma Lens for Electrons and Positrons Phys. Rev. Lett. 87, 244801 (2001) Built on early low-energy demonstration experiments in early to mid-nineties: FNAL (1990), JAPAN (1991), UCLA (1994)… Demonstrated plasma lensing of 28.5GeV beams

  8. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - + + + + + + + + + + + + + + + - + + + + + + + + + + + + + + + - - - - - - - - - + + + + + + + + + + + + + + + + - - + + + + + - + + + + + - + + + + + + + + + + + + + + + - - - - + + + + + + + + + + + + + + + - - - - - - - - - - - electron beam - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Ez E-157, E-162, E-164 and E-164X: All (e- or e+) Beam Driven PWFA LINEAR PWFA SCALING Decelerating Accelerating Ez: accelerating field N: # e-/bunch sz: gaussian bunch length kp: plasma wave number np: plasma density nb: beam density Short bunch! m m Forand or m However, when nb > np, non-linear or “blow-out” regime m Scaling laws valid?

  9. E-162, E-164 & E-164X: Common Experimental Apparatus A quick reminder of how we do these experiments in the FFTB… Located in the FFTB Ionizing Laser Pulse (193 nm) Streak Camera (1ps resolution) e- or e+ ∫Cdt Li Plasma ne≈2·1014 cm-3 L≈1.4 m X-Ray Diagnostic N=2·1010 sz=0.6 mm E=30 GeV Cerenkov Radiator Optical Transition Radiators Spectrometer Dump 25 m FFTB Not to scale!

  10. ne=0 ne≈1014 cm-3 2mm • Ideal Plasma Lens in Blow-Out Regime e- 2mm • Plasma Lens with Aberrations e+ Plasma Focusing of Electrons and Positrons • OTR images ≈1m from plasma exit Note: enx>eny

  11. Experiments at ORIONmay address limitations of plasma lenses High de-magnification plasma lens could help determine the ultimate limitations of plasma lenses. For a plasma lens with length equal to the focal length the de-magnification is given by: Want small emittance, large initial beam size, but enough beam density for blow-out Limitations due to geometric and chromatic aberrations: & J. J. Su et al Phys. Rev. A 41, 3321 (1990)

  12. E-157 E-162 Run 2 Plasma OFF sx (µm) Phase Advance  ne1/2L Phase Advance  ne1/2L Stable Propagation Through An Extended Plasma Beam matched to the plasma when: Physical Review Letters88, 154801 (2002) - Matching minimizes spot size variations and stabilize hose instability - Places a premium on getting small spots

  13. Stable Propagation Part II Electron Hose Instability? No significant instability observed in E-162 with np up to 21014 cm-3, and L=1.4 m - Hose instability grows as1exp((kbL)2/3), where kb=wp/(2g)1/2c=(npe2/e0me 2g)1/2c • E-162:np=21014 cm-3, L=1.4 m => e4.5=92 • E-164:np=61015 cm-3, L=0.3 m => e5.4=227 • E-164X:np=21017 cm-3, L=0.06 m => e5.4=227 no significant growth expected (?) • Theory assumes a preformed channel, neglects return currents… • Simulations include these effects and also predict little growth2 Phys. Rev. Lett. 67, 991 (1991) Phys. Rev. Lett. 88 , 125001 (2002)

  14. E-157: Electron Beam Refraction At Plasma–Gas Boundary Asymmetric Channel Beam Steering Symmetric Channel Beam Focusing Core + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + e- + + + + + + Plasma, ne - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Head q f rc=a(nb/ne)1/2rb qµ1/sinf • Vary plasma – e- beam angle f using UV pellicle • Beam centroid displacement @ BPM6130, 3.8 m from the plasma center q≈f o BPM DATA Impulse Model P. Muggli et al., Nature 411, 2001

  15. Experiment (Cherenkov images) Laser off Laser on 3-D OSIRIS PIC Simulation Refraction of an Electron Beam: Interplay between Simulation & Experiment l 1st 1-to-1 modeling of meter-scale experiment in 3-D! P. Muggli et al., Nature 411, 2001

  16. E-162: X-Ray Emission from Betatron Motion in a Plasma Wiggler Central Photon Energy = 14.2 keV Number of Photons = 6x105 Peak Spectral Brightness = 7x1018 [#/(sec-mrad2-mm2-0.1%)] Phys. Rev. Lett. 88, 135004 (2002)

  17. SM-LWFA electron energy spectrum S h o t 1 2 ( 1 0 k G ) 6 S h o t 2 6 ( 1 0 k G ) 1 0 S h o t 2 9 ( 5 k G ) S h o t 3 3 ( 5 k G ) S h o t 3 9 ( 2 . 5 k G ) 5 1 0 S h o t 4 0 ( 2 . 5 k G ) 4 1 0 Relative # of electrons/MeV/Steradian 3 1 0 6 8 1 0 2 0 4 0 6 0 8 0 1 0 0 2 0 0 E l e c t r o n e n e r g y ( i n M e V ) Plasmas Have Demonstrated Abilityto Support Large Amplitude Accelerating Electric Fields 100 MeV Laser Wakefield Results A. Ting et al NRL 200 MeV Laser Wakefield Results at Ecole Poly., France Accelerating Gradient ~200 GeV/m! Accelerating Gradient > 100 GeV/m V. Malka et al., Science 298, 1596 (2002) Need guiding or other technique to extend interaction distance beyond a few mm

  18. Particles in the core nearly de-accelerated to zero! Accelerated Tail Particles Average Gradient ~ 70 MeV/m PWFA Acceleration Experiments at ANL-AWA and FNL-A0 Head Tail Simulation N. Barov et al, PAC-2001-MOPC010, FERMILAB-CONF-01-365, Dec 2001. 3pp

  19. Beam Driven PWFA Single Bunch Energy Transformer OSIRIS Simulation Experimental Data Head Head • Average measured energy loss (slice average): 159±40 MeV • Average measured energy gain (slice average): 156 ±40 MeV (≈1.5108 e-/slice)

  20. A Few Examples of How ORION Might Help Address Some of These Issues

  21. 10 0 Gradient (GeV/m) -10 Flexible Electron Source  Opportunities for Plasma Wakefield Acceleration PWFA with optimized drive bunch for transformer ratios (>2) • Bunch compression (R56 < 0) produces a ramped profile with a sharp cutoff  high transformer ratio

  22. Drive and Witness Beam Production • Compressed, high-current 350 MeV drive pulse • Narrow energy spread, 60 MeV witness pulse, with continuously variable delay 0-120 ps Vernier Delay chicane Combiner chicane (also compresses drive pulse) Fast kicker and septum magnet HIGH ENERGY HALL NLCTA

  23. Use Witness Bunch Capability to Study EffectsOf beam Loading on Accelerating Wake 1+1 ≠ 2:Simulation vs. Linear Superposition Linearsuperposition Nonlinear wake 2nd beam charge density 1st beam charge density Nonlinear wake

  24. …and the Transverse (Focusing) Wake Focusing Force Also Effected By Beam Loading Linear superposition of focusing force Focusing force on r=0.5c/Wp Simulation result 2 beam charge densities

  25. Ion Channel Laser1:Proof of Principle at Optical Wavelengths “Accelerator-based synchrotron light sources play a pivotal role in the U.S. scientific community2. Free-electron lasers (FEL’s) can provide coherent radiation at wavelengths across the electromagnetic spectrum, and recently there has been growing interest in extending FEL’s down into the X-rays to provide researchers tools to understand the nature of proteins and chromosomes. … there is exciting potential for innovative science in the range of 8-20 keV, especially if a light source can be built with a high degree of coherence, temporal brevity, and high pulse energy. To date, the most promising candidate for such a source is a linac-driven X-ray FEL. It would be a unique instrument capable of opening new areas of research in physics, materials, chemistry and biology. Build on the experience of E-157/E-162/E-164 towards an ICL • Move beyond spontaneous x-rays to stimulated emission via the ICL (analogous to an FEL with plasma wiggler) • Requires many betatron oscillations therefore lower energy beam with high density plasma • 60MeV, 20cm long plasma of 6x1015 density for visible • 300MeV, 1.5m long plasma of 4x1014 density for ultraviolet (80nm) • ICL potential advantage over FEL: • Short wavelength with relatively lower gamma – less linac, better coupling • Shorter period and stronger wigglers via plasma ion column 1 D. H. Whittum et al Phys. Rev. Lett. 64, 2511 (1990). 2Report of The Basic Energy Sciences Advisory Committee Panel on Novel Coherent Light Sources, Workshop at Gaithersburg Maryland, January 1999. http://www.er.doe.gov/production/bes/BESAC/NCLS_rep.PDF

  26. Electron Beam Refraction at the Gas–Plasma Boundary e- & e+ Focusing X-ray Generation Wakefield acceleration qµ1/sinf q≈f o BPM Data – Model Beam Plasma Experiments: Observed a wide range of phenomena but still much to do • Focusing of electron beams and stable propagation through an extended plasma • Electron beam deflection analogous to refraction at the gas-plasma boundary • X-ray generation due to betatron motion in the blown-out plasma ion column • Large gradients (>100GeV/m) over mm scale distances • Smaller gradients (~100MeV/m) over meter scale distances Still much to do: • Quantify limits for plasma lenses due to chromatic and spherical aberrations • Test for continued robustness against instabilities such as electron hose • > GeV/m acceleration via shorter bunches and tailored longitudinal profiles • Plasma source development: higher densities over several meters • Extend radiation generation from spontaneous to stimulated emission via ICL • Load the plasma wake and preserve focusing properties of the ion channel • Load the plasma wake for acceleration with narrow energy spread and high extraction efficiency

  27. 2nd ORION Workshop February 18-20, 2003 Beam-Plasma Working Group Redwood Room “?” Prof. Tom Katsouleas WG Leader • We will focus on: • Plasma wakefield physics • Plasma lenses • Beam quality • Radiation generation • Instabilities • Shaped beams • Beam loading • Simulation and theory needs. • Particularly relevant are: • Ideas for experiments at ORION • Ideas for diagnostics, instruments and models that could support/improve experiments. • Requirements for diagnostics, instruments, beams and models (whether or not you have an idea of how to make them) that would enable/improve experiments.