Download - Beam Plasma Physics Experiments at ORION Mark Hogan SLAC 2 nd ORION Workshop February 18-20, 2003
Beam Plasma Physics Experimentsat ORION
Mark Hogan
SLAC
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
2nd ORION Workshop February 18-20, 2003
Recent Results III: Promise and Challenge
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
E-157 & E-162 have observed a wide range of phenomena with bothelectron and positron drive beams:
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DS
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R (µ
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K*Lne1/2
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=43 µm
N=910-5 (m rad)
0=1.15m
e- & e+ Focusing Wakefield acceleration
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SliceEnergyGain.graphn
e=1.31014 (cm-3)
ne=1.61014 (cm-3)
ne=2.01014 (cm-3)
ne=(2.3±0.1)1014 (cm-3)
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eV)
(ps)
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BPM data
(m
rad)
(mrad)
1/sin
≈
Electron Beam Refraction at the Gas–Plasma Boundary
o BPM Data
X-ray Generation
– Model
Phys. Rev. Lett. 2002, 2003
Nature 2002 Phys. Rev. Lett. 2002
To Science 2003
Laser Wake Field Accelerator(LWFA)
A single short-pulse of photons
Self Modulated Laser Wake Field Accelerator(SMLWFA)
Raman forward scattering instability
Plasma Beat Wave Accelerator(PBWA)
Two-frequencies, i.e., a train of pulses
Concepts For Plasma-Based AcceleratorsPioneered by J.M.Dawson
Plasma Wake Field Accelerator(PWFA)
A high energy electron (or positron) bunch
evolves to
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.
A 100 GeV-on-100 GeV e-e+ Collider
Based on Plasma Afterburners
50 GeV 50 GeV ee--
50 GeV 50 GeV ee++
e-WFA e+WFA
IP
LENSES
Afterburners
3 km
30 m
But can it lead to…?
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…
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
UCLA
LINEAR PWFA SCALING
Ez ,linear N
z2
kp z 2 or np 1
z2
However, when nb > np, non-linear or “blow-out” regime
Scaling laws valid?
Ez: accelerating fieldN: # e-/bunchz: gaussian bunch lengthkp: plasma wave numbernp: plasma densitynb: beam density
For and
++++++++++++++ ++++++++++++++++
----- --- ----------------
---- -----------
-------- ------- -------------------- - -
-
---- - -- ---
------ -- -- ---- - - - - - --
---- - -- - - - --- --
- -- - - - - -
---- - ----
------
electron beam
+ + + + + + + + + + ++ + + + + + + + + + + + + + ++ + + + + + + + + + + + + + +
+ + + + + + + + + + + + + + +-
- --
--- --
EzEz
Accelerating Decelerating
Short bunch!
kp r 1
E-157, E-162, E-164 and E-164X:All (e- or e+) Beam Driven PWFA
UCLA
Located in the FFTB
e- or e+
N=2·1010
z=0.6 mmE=30 GeV
IonizingLaser Pulse
(193 nm)Li Plasma
ne≈2·1014 cm-3
L≈1.4 m
CerenkovRadiator
Streak Camera(1ps resolution)
X-RayDiagnostic
Optical TransitionRadiators Dump
25 m
∫Cdt
FFTBNot to scale!
Spectrometer
E-162, E-164 & E-164X:Common Experimental Apparatus
A quick reminder of how we do these experiments in the FFTB…
UCLA
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e-
e+
ne=0 ne≈1014 cm-3
2mm
2mm
• Ideal Plasma Lens in Blow-Out Regime
• Plasma Lens with Aberrations
• OTR images ≈1m from plasma exit
Note: nx>ny
Plasma Focusing ofElectrons and Positrons
E-150 E-162 FFTB
G [T/m] > 106 >103 0.18
L [m] 0.003 1.4 1.12
Np [e-/cm3] 6.5x1018 2x1014 N/A
Regime N/A
np nb
nb np
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:
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02 p 2
2 2ncWant small emittance, large initial beam size, but enough beam density for blow-out
*
K
K
*
Limitations due to geometric and chromatic aberrations: &
J. J. Su et al Phys. Rev. A 41, 3321 (1990)
UCLA
Plasma OFF
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BetatronFitShortBetaXPSI.graph
Plasma OFF
Plasma ON
Envelope
x (µ
m)
L=1.4 m
0=14 µm
N
=1810-5 m-rad
0=6.1 cm
0=-0.6
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05160cedFIT.graph
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m)
=K*Lne1/2L
0 Plasma Entrance
=50 µm
N=1210-5 (m rad)
0=1.16m
E-157 E-162 Run 2
Phase Advance ne1/2L Phase Advance ne
1/2L
x (µ
m)
Beam matched to the plasma when: beam 2
p
c 2plasma
- Matching minimizes spot size variations and stabilize hose instability- Places a premium on getting small spots
Physical Review Letters 88, 154801 (2002)
Stable Propagation ThroughAn Extended Plasma
No significant instability observed in E-162 with
np up to 21014 cm-3, and L=1.4 m
- Hose instability grows as1 exp((kL)2/3), where k=p/(2)1/2c=(npe2/e0me 2)1/2c
– E-162: np=21014 cm-3, L=1.4 m => e4.5=92
– E-164: np=61015 cm-3, L=0.3 m => e5.4=227
– E-164X: np=21017 cm-3, L=0.06 m => e5.4=227
1. Phys. Rev. Lett. 67, 991 (1991)2. Phys. Rev. Lett. 88 , 125001 (2002)
Stable Propagation Part II
no significant growth expected (?)
- Theory assumes a preformed channel, neglects return currents…
- Simulations include these effects and also predict little growth2
Electron Hose Instability?
UCLA
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BPM data
(m
rad)
(mrad)
1/sin
≈o BPM DATA
Impulse Model
rc=(nb/ne)1/2rb
Head
Plasma, ne
AsymmetricChannel
Beam Steering
SymmetricChannel
Beam Focusing
e-++
++
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++++
+++++ + ++++- - - - - - - - -
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Core
E-157: Electron Beam Refraction At Plasma–Gas Boundary
P. Muggli et al., Nature 411, 2001
• Vary plasma – e- beam angle using UV pellicle
• Beam centroid displacement @ BPM6130, 3.8 m from the plasma center
UCLA
Refraction of an Electron Beam:Interplay between Simulation & Experiment
Laser off Laser on
3-D OSIRIS
PIC Simulation
Experiment(Cherenkov
images)
1st 1-to-1 modeling of meter-scale experiment in 3-D!
P. Muggli et al., Nature 411, 2001
UCLA
Phys. Rev. Lett. 88, 135004 (2002)
E-162: X-Ray Emission fromBetatron Motion in a Plasma Wiggler
Central Photon Energy = 14.2 keVNumber of Photons = 6x105
Peak Spectral Brightness = 7x1018
[#/(sec-mrad2-mm2-0.1%)]
V. Malka et al., Science 298, 1596 (2002)
200 MeV Laser Wakefield Resultsat Ecole Poly., France
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Sho t 12 (10 kG ) Sho t 26 (10 kG ) Shot 29 (5 kG )Shot 33 (5 kG ) Sho t 39 (2.5 kG) Sho t 40 (2.5 k G)
Re
lativ
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of
ele
ctro
ns/
Me
V/S
tera
dia
n
E lectron energy (in M eV)
SM-LWFA electron energy spectrum
Accelerating Gradient> 100 GeV/m
Accelerating Gradient~200 GeV/m!
100 MeV Laser Wakefield ResultsA. Ting et al NRL
Plasmas Have Demonstrated Abilityto Support Large Amplitude Accelerating Electric Fields
Need guiding or other technique to extend interaction distance beyond a few mm
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Accelerated Tail ParticlesAverage Gradient ~ 70 MeV/m
Particles in the core nearly de-accelerated to zero!
PWFA Acceleration Experiments at ANL-AWA and FNL-A0
N. Barov et al, PAC-2001-MOPC010, FERMILAB-CONF-01-365, Dec 2001. 3pp
HeadTail
Simulation
UCLA
Head Head
Beam Driven PWFASingle Bunch Energy Transformer
OSIRIS Simulation
Average measured energy loss (slice average): 159±40 MeV Average measured energy gain (slice average): 156 ±40 MeV
(≈1.5108 e-/slice)
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SliceEnergyGain3curves.graph
ne=1.61014 (cm-3)
ne=2.01014 (cm-3)
ne=(2.3±0.1)1014 (cm-3)
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e E
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y (M
eV)
(ps)
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Experimental Data
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A Few Examples of How
ORION Might Help Address Some of These Issues
Flexible Electron Source Opportunities for Plasma Wakefield Acceleration
• Bunch compression (R56 < 0) produces a ramped profile with a sharp cutoff high transformer ratio
/ (a.u.)p p
(a.u.)z
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(a)
Optimum profile
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dien
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eV/m
)
PWFA with optimized drive bunch for transformer ratios (>2)
0-120 ps Vernier Delay
chicane
Fast kicker and septum
magnet
Combiner chicane(also compresses
drive pulse)
•Compressed, high-current 350 MeV drive pulse
•Narrow energy spread, 60 MeV witness pulse, with continuously variable delay
Drive and Witness Beam Production
HIGH ENERGY HALLNLCTA
1+1 ≠ 2:Simulation vs. Linear Superposition
2nd beam charge density
1st beam charge density
Linear superposition
Nonlinear wake
Nonlinear wake
Use Witness Bunch Capability to Study EffectsOf beam Loading on Accelerating Wake
Focusing Force Also Effected By Beam Loading
Focusing force on r=0.5c/Wp
2 beam charge densities
Linear superposition of focusing force
Simulation result
…and the Transverse (Focusing) Wake
Ion Channel Laser1:Proof of Principle at Optical Wavelengths
“Accelerator-based synchrotron light sources play a pivotal role in the U.S. scientific community 2. 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.
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
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
Build on the experience of E-157/E-162/E-164 towards an ICL
r 22
1 K 2
2 ()2
K r0
c
Beam Plasma Experiments:Observed a wide range of phenomena but still much to do
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=43 µm
N=910-5 (m rad)
0=1.15m
e- & e+ Focusing Wakefield acceleration
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SliceEnergyGain.graphn
e=1.31014 (cm-3)
ne=1.61014 (cm-3)
ne=2.01014 (cm-3)
ne=(2.3±0.1)1014 (cm-3)
Rel
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e E
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y (M
eV)
(ps)
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BPM data
(m
rad)
(mrad)
1/sin
≈
Electron Beam Refraction at the Gas–Plasma Boundary
o BPM Data
X-ray Generation
– Model
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
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
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.
Redwood Room “?”
Prof. Tom Katsouleas WG Leader
2nd ORION Workshop February 18-20, 2003
Beam-Plasma Working Group