Beam Plasma Physics Experiments at ORION

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

• 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

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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 GasPlasma
Boundary
e- e Focusing
Wakefield acceleration
X-ray Generation
qµ1/sinf
qf
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

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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

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But can it lead to?
A 100 GeV-on-100 GeV e-e ColliderBased on
Plasma Afterburners
3 km
Afterburners
30 m
LENSES
50 GeV e-
50 GeV e
e-WFA
eWFA
IP
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Many Issues Need to Be Addressed First
1. Development of plasma sources capable of
producing densities gt 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
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E-150 Plasma Lens for Electrons and Positrons
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
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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 For and
or

• m However, when nb gt np, non-linear or
  blow-out regime
• m Scaling laws valid?

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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)
e- or e
Streak Camera (1ps resolution)
?Cdt
Li Plasma ne21014 cm-3 L1.4 m
X-Ray Diagnostic
N21010 sz0.6 mm E30 GeV
Cerenkov Radiator
Optical Transition Radiators
Spectrometer
Dump
25 m
FFTB
Not to scale!
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Plasma Focusing of Electrons and Positrons
OTR images 1m from plasma exit
Note enxgteny
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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)
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Stable Propagation Through An Extended Plasma
Beam matched to the plasma when
Physical Review Letters 88, 154801 (2002)
- Matching minimizes spot size variations and
stabilize hose instability - Places a premium on
getting small spots
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Stable Propagation Part II
Electron Hose Instability?
? No significant instability observed in E-162
with np up to 2?1014 cm-3, and L1.4 m
- Hose instability grows as1 exp((kbL)2/3), where
kbwp/(2g)1/2c(npe2/e0me 2g)1/2c

• E-162 np2?1014 cm-3, L1.4 m gt e4.592
• E-164 np6?1015 cm-3, L0.3 m gt e5.4227
• E-164X np2?1017 cm-3, L0.06 m gt e5.4227

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)

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Head
q
f
rca(nb/ne)1/2rb
qµ1/sinf
Vary plasma e- beam angle f using UV
pellicle Beam centroid displacement _at_
BPM6130, 3.8 m from the plasma center
qf
o BPM DATA
Impulse Model
P. Muggli et al., Nature 411, 2001
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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
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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)
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Plasmas Have Demonstrated Abilityto Support
Large Amplitude Accelerating Electric Fields
200 MeV Laser Wakefield Results at Ecole Poly.,
France
100 MeV Laser Wakefield Results A. Ting et al NRL
Accelerating Gradient 200 GeV/m!
Accelerating Gradient gt 100 GeV/m
V. Malka et al., Science 298, 1596 (2002)
Need guiding or other technique to extend
interaction distance beyond a few mm
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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
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Beam Driven PWFA Single Bunch Energy Transformer
OSIRIS Simulation
Experimental Data
Head
Head

• Average measured energy loss (slice average)
  15940 MeV
• Average measured energy gain (slice average)
  156 40 MeV
• (1.5?108 e-/slice)

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A Few Examples of How ORION Might Help Address
Some of These Issues
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Flexible Electron Source ? Opportunities for
Plasma Wakefield Acceleration
PWFA with optimized drive bunch for transformer
ratios (gt2)

• Bunch compression (R56 lt 0) produces a ramped
  profile with a sharp cutoff ? high transformer
  ratio

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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
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11 ? 2Simulation vs. Linear Superposition
Use Witness Bunch Capability to Study EffectsOf
beam Loading on Accelerating Wake
Linear superposition
Nonlinear wake
2nd beam charge density
1st beam charge density
Nonlinear wake
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Focusing Force Also Effected By Beam Loading
and the Transverse (Focusing) Wake
Linear superposition of focusing force
Focusing force on r0.5c/Wp
Simulation result
2 beam charge densities
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Ion Channel Laser1Proof of Principle at Optical
Wavelengths
Accelerator-based synchrotron light sources
play a pivotal role in the U.S. scientific
community2. Free-electron lasers (FELs) can
provide coherent radiation at wavelengths across
the electromagnetic spectrum, and recently there
has been growing interest in extending FELs 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
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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 (gt100GeV/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
• gt 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

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Beam-Plasma Working Group
2nd ORION Workshop February 18-20, 2003
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.