plasma acceleration presented by: mark hogan on behalf of: the e-164/e-164x collaboration
DESCRIPTION
Plasma Acceleration Presented by: Mark Hogan On behalf of: The E-164/E-164X Collaboration C. D. Barnes, I. Blumenfeld, F.J. Decker, P. Emma, M.J. Hogan * , R. Ischebeck, R. Iverson, N. Kirby, P. Krejcik, C. L. O'Connell, R.H. Siemann and D. Walz Stanford Linear Accelerator Center - PowerPoint PPT PresentationTRANSCRIPT
1Work supported by Department of Energy contracts DE-AC02-76SF00515 (SLAC), DE-FG03-92ER40745, DE-FG03-98DP00211, DE-FG03-92ER40727, DE-AC-0376SF0098, and National Science Foundation grants No. ECS-9632735, DMS-9722121 and PHY-0078715.
Work supported by Department of Energy contracts DE-AC02-76SF00515 (SLAC), DE-FG03-92ER40745, DE-FG03-98DP00211, DE-FG03-92ER40727, DE-AC-0376SF0098, and National Science Foundation grants No. ECS-9632735, DMS-9722121 and PHY-0078715.
Plasma AccelerationPresented by: Mark Hogan
On behalf of: The E-164/E-164X Collaboration
C. D. Barnes, I. Blumenfeld, F.J. Decker, P. Emma, M.J. Hogan*, R. Ischebeck, R. Iverson,
N. Kirby, P. Krejcik, C. L. O'Connell, R.H. Siemann and D. WalzStanford Linear Accelerator Center
C. E. Clayton, C. Huang, D. K. Johnson, C. Joshi*, W. Lu, K. A. Marsh, W. B. Mori and M. Zhou
University of California, Los Angeles
S. Deng, T. Katsouleas*, P. Muggli and E. OzUniversity of Southern California
U C L A
Laser Driven Plasma Accelerators:
• Accelerating Gradients > 100GeV/m (measured)• Narrow Energy Spread Bunches• Interaction Length limited to mm’s
Beam Driven Plasma Accelerators:
Large Gradients:• Accelerating Gradients > 30 GeV/m (measured!)• Interaction Length not limited
Unique SLAC Facilities:• FFTB• High Beam Energy• Short Bunch Length• High Peak Current• Power Density• e- & e+
Scientific Question:• Can one make & sustain high gradients in plasmas for lengths that give significant energy gain?
Laser Driven Plasma Accelerators:
• Accelerating Gradients > 100GeV/m (measured)• Narrow Energy Spread Bunches• Interaction Length limited to mm’s
Beam Driven Plasma Accelerators:
Large Gradients:• Accelerating Gradients > 30 GeV/m (measured!)• Interaction Length not limited
Unique SLAC Facilities:• FFTB• High Beam Energy• Short Bunch Length• High Peak Current• Power Density• e- & e+
Scientific Question:• Can one make & sustain high gradients in plasmas for lengths that give significant energy gain?
Plasma AcceleratorsShowing Great Promise!
U C L A
PWFA:Plasma Wakefield Acceleration
Ez: accelerating fieldN: # e-/bunchz: gaussian bunch lengthkp: plasma wave numbernp: plasma densitynb: beam density
Ez,linear∝Nσ z
2
kpσz ≅ 2 or np ∝1σ z
2For and
++++++++++++++ ++++++++++++++++
----- -------------------
---- -----------
----------------------------------- --
-
---- ------
-------- -- --------- --
---- - --- - - --- --
- -- - -- - -
---------
------
electron beam
+ + + + + + + + + + ++ + + + + + + + + + + + + + ++ + + + + + + + + + + + + + +
+ + + + + + + + + + + + + + +-
- --
--- --
EzEz
AcceleratingDecelerating
Short bunch!
€
kpσ r <<1
Linear PWFA Theory:
Looking at issues associated with applying the large focusing (MT/m) and
accelerating (GeV/m) gradients in plasmas to high energy physics and colliders Built on E-157 & E-162 which observed a wide range of phenomena with both
electron and positron drive beams: focusing, acceleration/de-acceleration, X-ray
emission, refraction, tests for hose instability…
A single bunch from the linac drives a large amplitude plasma wave which focus and accelerates particles For a single bunch the plasma works as an energy transformer and transfers energy from the head to the tail
U C L A
Located in the FFTB
FFTB
PWFA Experiments @ SLACShare Common Apparatus
e-
N=1.81010
z=20-12µmE=28.5 GeV
Optical TransitionRadiators
Li Plasma Gas Cell: H2, Xe, NO
ne≈0-1018 cm-3
L≈2.5-20 cmPlasma light
X-RayDiagnostic,
e-/e+
Production
CherenkovRadiator Dump
∫Cdt
ImagingSpectrometer
xz
y
EnergySpectrum“X-ray”
25m
CoherentTransition
Radiation andInterferometer
FFTB
Wakefield Acceleration e-
Focusing e-
Phys. Rev. Lett. 88, 154801 (2002)
Beam-Plasma Experimental Results (6 Highlights)
X-ray Generation
Phys. Rev. Lett. 88, 135004 (2002)
0
50
100
150
200
250
300
-2 0 2 4 6 8 10 12
05160cedFIT.graph
ψ= *K L∝ne1/2L
0 Plasma Entrance
=50µm
εN=12×10-5( )m rad
β0=1.16m
0
100
200
300
400
500
600
0 2 4 6 8 10 12 14
BetatronFitShortBetaXPSI.graph
Plasma OFF
Plasma ON
Envelope
Ψ
=1.4L m0=14µm
εN=18×10-5 -m rad
β0=6.1cm
α0=-0.6
Phase Advance Ψ ne1/2L
Matching e-
Phase Advance Ψ ne1/2L
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
-8 -4 0 4 8
05190cec+m2.txt 8:26:53 PM 6/21/00impulse model
BPM data
θ
( )mrad
φ( )mrad
θ1/sin
θ≈o BPM Data– Model
Electron Beam Refraction at the Gas–Plasma Boundary
Nature 411, 43 (3 May 2001)
Wakefield Acceleration e+
Phys. Rev. Lett. 90, 214801 (2003)Phys. Rev. Lett. 93, 014802 (2004)
Phys. Rev. Lett. 93, 014802 (2004)
U C L A
28 GeV28 GeV
Existing bends compress to Existing bends compress to <100 fsec<100 fsec
~1 Å~1 Å
Add 12-meter chicane compressor Add 12-meter chicane compressor in linac at 1/3-point (9 GeV)in linac at 1/3-point (9 GeV)
Add 12-meter chicane compressor Add 12-meter chicane compressor in linac at 1/3-point (9 GeV)in linac at 1/3-point (9 GeV)
Damping RingDamping Ring
9 ps9 ps 0.4 ps0.4 ps<100 fs<100 fs
50 ps50 ps
SLAC LinacSLAC Linac
1 GeV1 GeV 20-50 GeV20-50 GeV
FFTBFFTBRTLRTL
30 kA30 kA
80 fsec FWHM80 fsec FWHM
1.5%1.5%
Short Bunch GenerationIn The SLAC Linac
• Bunch length/current profile is the convolution of an incoming energy spectrum and the magnetic compression• Dial FFTB R56 & linac phase, then measure incoming energy spectrum.
0
0.4
0.8
1.2
1.6
-100 -50 0 50 100CombinedCTRInterferogramsSm 0
10
20
30
40
50
60
0 5 10 15 20 25 30 35 40
SigmazMylar12.7_3WandBS
Autocorrelationz( )µm
/ w o Filtering
w Filtering
z≈9 µm
≈60 fs
z ≈ 9 µm
z≈18 µm
GaussianBunch
or
First Measurement of SLAC Ultra-short Bunch Length!
QuickTime™ and aTIFF (LZW) decompressor
are needed to see this picture.
Autocorrelation:
CTR Michelson Interferometer• Fabry-Perot resonance:=2d/nm, m=1,2,…, n=index of refraction• Modulation/dips in the interferogram• Smaller measured width:Autocorrelation < bunch !• Other issues under investigation:- Detector response (pyro vs. Golay)- Alternate materials:HDPE, TPX, Si, Diamond ($$$)
CTR Michelson Interferometer• Fabry-Perot resonance:=2d/nm, m=1,2,…, n=index of refraction• Modulation/dips in the interferogram• Smaller measured width:Autocorrelation < bunch !• Other issues under investigation:- Detector response (pyro vs. Golay)- Alternate materials:HDPE, TPX, Si, Diamond ($$$)
U C L A
Non-Invasive Energy SpectrometerUpstream of Plasma
U C L A
Phase Space Retrieval via LiTrack*
*K. Bane & P. Emma
• Extension of previous work on SLC- More compression stages- More free parameters- Shorter bunches• Requires good measurements, good intuition or really good guessing!• Not automated (yet!)• Single shot and non-destructive!
• Extension of previous work on SLC- More compression stages- More free parameters- Shorter bunches• Requires good measurements, good intuition or really good guessing!• Not automated (yet!)• Single shot and non-destructive!
U C L A
Plasma Source Starts withMetal Vapor in a Heat-Pipe Oven
€
E = 6GV /mN
2x1010
20μ
σ r
100μ
σ z
Peak Field For A Gaussian Bunch: Ionization Rate for Li:
See D. Bruhwiler et al, Physics of Plasmas 2003
Space charge fields are high enough to field (tunnel) ionize - no laser!- No timing or alignment issues- Plasma recombination not an issue
- However, can’t just turn it off! - Ablation of the head
0 0Pressure
zLi HeHe
Boundary Layers
OpticalWindowCoolingJacketCoolingJacket
HeaterWick
InsulationPumpHe
OpticalWindow
L
0 0 zLi HeHe
Boundary Layers
OpticalWindowCoolingJacketCoolingJacket
HeaterWick
InsulationPumpHe
OpticalWindow
L
U C L A
Accelerating Gradient > 27 GeV/m!(Sustained Over 10cm)
No Plasma np = 2.8 x 1017 e-/cm3
Ene
rgy
[GeV
]
31.5
30.5
29.5
28.5
27.5
26.5
25.5
24.5
• Large energy spread after the plasma is an artifact of doing single bunch experiments
• Electrons have gained > 2.7 GeV over maximum incoming energy in 10cm
• Confirmation of predicted dramatic increase in gradient with move to short bunches
• First time a PWFA has gained more than 1 GeV
• Two orders of magnitude larger than previous beam-driven results
• Future experiments will accelerate a second “witness” bunch
• Large energy spread after the plasma is an artifact of doing single bunch experiments
• Electrons have gained > 2.7 GeV over maximum incoming energy in 10cm
• Confirmation of predicted dramatic increase in gradient with move to short bunches
• First time a PWFA has gained more than 1 GeV
• Two orders of magnitude larger than previous beam-driven results
• Future experiments will accelerate a second “witness” bunch
M.J. Hogan et al. Phys. Rev. Lett. 95, 054802 (2005)
Summer 2004:
• Results Recently
Published
• Outdated within two
weeks!
Summer 2005:
• Increased beamline
apertures
• Plasma Length increased
from
10 to 30 cm
Summer 2004:
• Results Recently
Published
• Outdated within two
weeks!
Summer 2005:
• Increased beamline
apertures
• Plasma Length increased
from
10 to 30 cm
• Energy Gain > 10GeV!
…but spectrometer
redesign necessary to
transport more of the
low energy electrons
14
Access to Access to timetime coordinate coordinate along bunchalong bunch
Exploit Exploit Position-TimePosition-Time Correlation on Correlation on ee-- bunch in FFTB Dog Leg bunch in FFTB Dog Legto create separate drive and witness bunchto create separate drive and witness bunch
x E/E t
1. Insert tantalum blade as notch collimator
2 Do not compress fully to preserve two bunches separated in time
Test of Notch Collimator - December 2005
15
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Low Energy
High Energy
Energy Spectrum Before Plasma:
Energy Spectrum After Plasma:
Shot # (Time)
Ta Blade100-300µm Wide1.6cm Long (4 X0)
• Acceleration correlates with collimator location (Energy)• No signature of temporally narrow witness bunch - yet!• Other interesting phenomena also correlate (see next slide)• Collimated spectra more complicated than anticipated
• Acceleration correlates with collimator location (Energy)• No signature of temporally narrow witness bunch - yet!• Other interesting phenomena also correlate (see next slide)• Collimated spectra more complicated than anticipated
Energy Loss
Energy Gain
Test of Notch Collimator - December 2005
Always New Things to Look At! (Part 1)
Narrow Energy Spread!
En
erg
y [G
eV]
QuickTime™ and aTIFF (LZW) decompressor
are needed to see this picture.
Trapped Particles Two Main Features• 4 times more charge• 104 more light!
Two Main Features• 4 times more charge• 104 more light!
Always New Things to Look At! (Part 2)
Dipole
10cm
30cm 20cm
• Particles are trapped and accelerated out of the plasma
• Trapped particle energy scales with plasma length: 5GeV @ 30cm
• Primary beam (28.5GeV) is also radiating after the plasma!
• Particles are trapped and accelerated out of the plasma
• Trapped particle energy scales with plasma length: 5GeV @ 30cm
• Primary beam (28.5GeV) is also radiating after the plasma!
Always New Things to Look At! (Part 2)
U C L A
• Create two bunches via notch collimator in FFTB and accelerate witness bunch with narrow energy spread
Future Experiments - Part 1(Next 2.5 months)
"Far better is it to dare mighty things, to win glorious triumphs, even though checkered by failure, than to take rank with those poor spirits who neither enjoy much nor suffer much, because they live in the gray twilight that knows not victory or defeat."
Theodore Roosevelt, 1899
• FFTB will soon be demolished to make way for LCLS
Use ~ 1 Meter-long Plasma toDouble the Energy of Part of the
Incoming Beam28.5 GeV 57GeV
What should we do to go out with a bang?Make the Highest Energy Electrons Ever @ SLAC!
U C L A
Future Experiments - Part 2(A Couple Years)
SABER (South Arc Beamline Experimental Region):
5.7GeV in 39cm
Evolution of a positron beam/wakefiled and final energy gain in a self-ionized plasma
€
N b = 8.79 ×109,σ r = 11μm, σ z = 19.55μm, np = 1.8 ×1017cm−3
Short Pulse e+ Are the Frontier:
U C L A
Over the past 5 years20 Peer reviewed publications covering all aspects of beam plasma interactions: Focusing (e- & e+), Transport, Refraction, Radiation Production, Acceleration (e- & e+)
E-164X Accomplishments
Demonstration of Field Ionized Plasma Source
En
erg
y [G
eV
]
31.5
30.5
29.5
28.5
27.5
26.5
25.5
24.5
No Plasma Np = 2.8x1017 e-/cc
Measured Accelerating Gradients > 27 GeV/m (over 30cm) in a PWFA
€
z ≈ 9μm
0
0.4
0.8
1.2
1.6
-100 -50 0 50 100CombinedCTRInterferogramsSm
First measurement of the SLAC Ultra-short Bunch
Length
Position [mm]
Au
toco
rre
latio
n A
mp
litu
de
[a
.u.]
Plasma Wakefield AcceleratorResearch Summary
Bright Future:Two bunch experiment, Energy Doubler, and longer term positrons @ SABER