Plasma Wakefield Acceleration Presented by: Bob Siemann On behalf - - PDF document

1

Dec 21, 2005 HEPAP Accel Research Subpanel 1

Bob Siemann SLAC HEPAP Subpanel on Accelerator Research

• Plasma Wakefield Acceleration
• Facilities and Opportunities
• Concluding Remarks

Plasma Wakefield Acceleration

Presented by: Bob Siemann On behalf of: The E157, E162, E-164, E-164X, E167 Collaborations

• S. Deng,* T. Katsouleas, S. Lee,* R. Maeda, P. Muggli, E. Oz* and W. Quillinan

University of Southern California

• B. Blue,* C. E. Clayton, E. Dodd, R. A. Fonseca, R. Hemker,* C. Huang,*

D.K. Johnson,* C. Joshi, W. Lu,* K.A. Marsh, W. B. Mori, C. Ren,

• F. Tsung, S. Wang* and M. Zhou*

University of California, Los Angeles

• R. Assmann, C. D. Barnes,* I. Blumenfeld,* F.-J. Decker, P. Emma, M.J. Hogan,
• R. Ischebeck, R.H. Iverson, N.A. Kirby,* P. Krejcik, C. O'Connell,*
• P. Raimondi, S.Rokni, R.H. Siemann, D. Walz and D. Whittum

Stanford Linear Accelerator Center

• P. Catravas, S. Chattopadhyay, E. Esarey and W. P. Leemans

Lawrence Berkeley National Laboratory

The authors of at least one of our peer-reviewed papers * = the 14 students in these collaborations

2

Dec 21, 2005 HEPAP Accel Research Subpanel 3

Plasma Accelerators Showing Great Promise

Scientific Question: Accelerating Gradients > 100 GeV/m have been measured in laser-plasma interactions. Can one make & sustain such high gradients for lengths that give significant energy gain? Scientific Question: Accelerating Gradients > 100 GeV/m have been measured in laser-plasma interactions. Can one make & sustain such high gradients for lengths that give significant energy gain? Unique SLAC Facilities The SLAC Linac & FFTB which have

• High Beam Energy
• Short Bunch Length
• High Peak Current
• Power Density
• e- & e+

We are studying the underlying beam/plasma physics and looking at issues associated with applying the large focusing (MT/m) and accelerating (GeV/m) gradients in plasmas to high energy physics and colliders

Dec 21, 2005 HEPAP Accel Research Subpanel 4

Plasma Wakefield Acceleration - I

Ez: accelerating field N: # e-/bunch σz: gaussian bunch length kp: plasma wave number np: plasma density nb: beam density

PWFA Accelerator Concept

+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + +

• -
• -
• --- -
• -
• ----- - -- -
• -
• - - -
• --
• -
• -
• -
• e

l e c t r

• n

b e a m

+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +

• -
• Ez

Ez Accelerating Decelerating

Ez,linear ∝ N σ z

2

⇒ Short bunch!

• + +

+ +

Ions Plasma e- Fully relativistic plasma simulations agree with σz dependence

3

Dec 21, 2005 HEPAP Accel Research Subpanel 5

Plasma Wakefield Acceleration - II

Closer to Reality

+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + +

• -
• -
• --- -
• -
• ----- - -- -
• -
• - - -
• --
• -
• -
• -
• e

l e c t r

• n

b e a m

+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +

• -
• Ez

Ez Accelerating Decelerating

+ + + +

Plasma e-

In most of the experiments a single bunch from the linac drives a large amplitude plasma wave which focus and accelerates particles AND the tail of that bunch is used to measure the accelerating field. 2

1

p z

n σ ∝

~

z plasma

σ λ π

2

~

z z

E N σ

⇒

When combined with ⇒

Dec 21, 2005 HEPAP Accel Research Subpanel 6

Plasma Wakefield Acceleration - III

Reality

4

Dec 21, 2005 HEPAP Accel Research Subpanel 7

Located in the FFTB

FFTB

PWFA Experiments

e-

N=1.8×1010 σz=20-12µm E=28.5 GeV Optical Transition Radiators Li Plasma Gas Cell: H2, Xe, NO ne≈0-1018 cm-3 L≈2.5-20 cm Plasma light X-Ray Diagnostic, e-/e+ Production Cherenkov Radiator Dump

∫Cdt

Imaging Spectrometer

x z y

Energy Spectrum “X-ray” 25m Coherent Transition Radiation and Interferometer

FFTB

Positron Source North Damping Ring Linac South Damping Ring e-gun End Station A (ESA) Beam Switch Yard (BSY) PEP II

FFTB

Positron Return Line 3 km

Dec 21, 2005 HEPAP Accel Research Subpanel 8

Evolution of One Part Of the Apparatus

Be window

Upstream OTR

water jacket

Li plasma 1x1014cm-3 Li plasma 1x1014cm-3 Downstream OTR 1.4 m ArF laser (193 nm) to photoionize Li vapor 2x1010 σz = 600 μm

Toroid Magnet

Cherenkov & OTR filter wheels long λ auto- correlator

OTR, CTR, plasma light (spectrograph & gated camera) Cherenkov cell

3x1017 .3 m 2x1010 σz = 15 μm

Early Experiments The Present Run The SLAC linac and FFTB: A stable yet flexible resource and facility

• Develop experience & expertise
• Explore physics

5

Dec 21, 2005 HEPAP Accel Research Subpanel 9

3 Highlights of Early Experimental Results (σz = 600 μm)

Positron Acceleration

• 0.3
• 0.2
• 0.1

0.1 0.2 0.3

• 8
• 4

4 8

05190cec+m2.txt 8:26:53 PM 6/21/00

impulse model BPM data

θ (mrad) φ (mrad)

θ∝1/sinφ θ≈φ

• BPM Data

– Model

Electron Beam Refraction at the Gas– Plasma Boundary Nature 411, 43 (3 May 2001)

Matching e-

100 200 300 400 500 600 2 4 6 8 10 12 14

BetatronFitShortBetaXPSI.graph

Plasma OFF Plasma ON Envelope

σx (µm) Ψ L=1.4 m σ0=14 µm εN=18×10-5 m-rad β0=6.1 cm α0=-0.6

Phase Advance Ψ ∝ ne

1/2L

• Phys. Rev. Lett. 93, 014802 (2004)
• Phys. Rev. Lett. 90, 214801 (2003)

Dec 21, 2005 HEPAP Accel Research Subpanel 10

Short Bunches

• Phys. Rev. Lett. 93, 014802 (2004)

( )

2 z z

E N σ ∝

0.1 0.2 0.3 5 10 15 20 25 30 z /mm I /kA Ipk = 30.631 kA σz= 28.0 µm (FWHM: 24.6 µm, Gauss: 11.0 µm) 0.5 1 1.5 2 −2 2 4 ΔE/〈E〉 /% n/103 σE/〈E〉=1.51% (FWHM: 4.33%) 0.1 0.2 0.3 −2 2 4 z /mm ΔE/〈E〉 /% 〈E〉 = 28.493 GeV, Ne = 2.133×1010 ppb

28 GeV 28 GeV

Add 12-meter chicane compressor in linac at 1/3-point (9 GeV) Add 12 Add 12-

• meter chicane compressor

meter chicane compressor in linac at 1/3 in linac at 1/3-

• point (9 GeV)

point (9 GeV)

Damping Ring Damping Ring 9 ps 9 ps 0.4 ps 0.4 ps <100 fs <100 fs 50 ps 50 ps

SLAC Linac SLAC Linac

1 GeV 1 GeV 20 20-

• 50 GeV

50 GeV FFTB FFTB

RTL RTL

30 kA 30 kA 80 fsec FWHM 80 fsec FWHM 1.5% 1.5%

← Increasing Bunch Length Energy Spectrum Plasma Production by Tunnel Ionization

No ionization Complete ionization

6

Dec 21, 2005 HEPAP Accel Research Subpanel 11

• Electrons have gained > 2.7

GeV over maximum incoming energy in 10cm

• Confirmation of predicted

dramatic increase in gradient with short bunches

• First time a PWFA has gained

more than 1 GeV & two orders

• f magnitude larger than

previous beam-driven results

• Electrons have gained > 2.7

GeV over maximum incoming energy in 10cm

• Confirmation of predicted

dramatic increase in gradient with short bunches

• First time a PWFA has gained

more than 1 GeV & two orders

• f magnitude larger than

previous beam-driven results

Summer 2004: Accelerating Gradient > 27 GeV/m! (Sustained Over 10cm)*

No Plasma np = 2.8x1017 cm-3

* Large energy spread after the plasma is an artifact of doing single bunch experiments

Dec 21, 2005 HEPAP Accel Research Subpanel 12

Summer 2005: Next PRL Cover??

• Increased Beamline apertures
• Increased plasma length to 30

cm

• Electrons have gained > 10 GeV
• Increased Beamline apertures
• Increased plasma length to 30

cm

• Electrons have gained > 10 GeV

Large amplitude plasma waves are sustained for at least 30 cm!

7

Dec 21, 2005 HEPAP Accel Research Subpanel 13

Always New Things to Look At! Narrow Energy Spread Trapped Particles

Coherent (at λ ~ 500 nm) Cherenkov Radiation ~ 80 MeV Either > 500 MeV or bunching of the 28.5 GeV beam Next Step = 2-bunches produced by collimation

Dec 21, 2005 HEPAP Accel Research Subpanel 14

Future Plasma Acceleration Research Three different time horizons

• I. The remainder of the lifetime of the FFTB
• two bunch experiment
• understanding of the trapped particles from the plasma
• the energy doubling experiment
• II. The Intermediate term – experiments at the NLC Test Accelerator
• III. Long term - high energy experiments with short bunch e+ at SABER

Return to these in a few minutes

Li plasma 3x1017cm-3 Li plasma 3x1017cm-3 1.0 m 2x1010 σz = 15 μm

Dipole Dump Magnet Incident Energy

8

Dec 21, 2005 HEPAP Accel Research Subpanel 15

Facilities and Opportunities

Dec 21, 2005 HEPAP Accel Research Subpanel 16

Facilities and Opportunities

The plasma acceleration program at the FFTB provides an excellent example of the ingredients of a successful accelerator research program Compelling scientific questions University/national lab collaboration – both benefit state-of-the-art facilities Experienced experimentalists, powerful scientific apparatus and rapid scientific progress follow naturally from these three

9

Dec 21, 2005 HEPAP Accel Research Subpanel 17

Scientific Questions & Collaborations

Potential of plasma acceleration (USC/UCLA/SLAC) The photonics revolution & particle acceleration (Stanford/SLAC) Limits of high gradient acceleration (ANL/LBNL/Maryland/MIT/NRL/SLAC)

Positron Acceleration

Dec 21, 2005 HEPAP Accel Research Subpanel 18

State-of-the Art Facilities: The NLCTA

NLCTA

The NLCTA is located in End Station B, which is the location of some ILC & LARP R&D, high gradient research, and the laser acceleration experiment (E163)

• Significant investment in the past for the warm

ILC – 300 MeV X-band linac

• Augmented with an S-band photoinjector for E-

163

• Additional X-band and L-band RF power is

being developed or is available

• Ti:Sapphire laser system installed
• Space for experiments at 60 MeV and at 300

MeV

10

Dec 21, 2005 HEPAP Accel Research Subpanel 19

Accelerator Research at the NLCTA

Use of the NLCTA for ILC related R&D continues and this R&D relies on some of the same systems as the non-ILC accelerator research Concentrate on non-ILC accelerator R&D at the NLCTA for this subpanel

• High gradient RF studies – Sami Tantawi’s talk
• Laser acceleration – Bob Byer’s talk
• Plasma acceleration – Experiments at the

NLCTA in the intermediate term NLCTA Laser Room E163 Hall 60 MeV beam 300 MeV beam An example - Drive-witness configuration with variable delay Plasma Experiment Location

Dec 21, 2005 HEPAP Accel Research Subpanel 20

State-of-the Art Facilities:

SABER

The FFTB has been a gold mine for science

• Plasma acceleration (E157, E162, E164, E164X, E167)
• Plasma focusing (E150)
• Positron production (E166)
• High energy cosmic rays (FLASH (E165))
• Short pulse x-ray physics (SPPS)

The LCLS will be constructed in the straight-ahead line presently occupied by the FFTB, and SABER has been proposed as a replacement. Short Bunches

11

Dec 21, 2005 HEPAP Accel Research Subpanel 21

Science at SABER

The SABER white paper includes science in

• Plasma Wakefield Acceleration and Beam-Plasma Physics
• Inverse Compton Scattering
• An Intense THz Light Source for Surface Chemistry
• Magnetism and Solid State Physics
• Laboratory Astrophysics Experiments

Energy Up to 30 GeV nominal Charge per pulse 3 nC e

• or e

+ per pulse with full compression; 5 nC

without full compression. Pulse length at IP 30 μm with 4 % momentum spread; 42 μm with 1.5 % momentum spread. Spot size at IP 10 μm nominal (η = η’ = 0) Momentum spread 4 % full width with full compression; < 0.5 % full width without compression. Drift space available for experimental apparatus 2 m from last quadrupole to focal point. Approximately 23 m from the focal point to the Arc 3 magnets

Dec 21, 2005 HEPAP Accel Research Subpanel 22

Plasma Experiments at SABER

5.7 GeV in 39cm Evolution of a positron beam/wakefield and final energy gain in a self-ionized plasma

Short Pulse e+ Are the Frontier

N = 8.8x109 σr = 11 μm σz = 19.6 μm np = 1.8x1017 cm-3

12

Dec 21, 2005 HEPAP Accel Research Subpanel 23

Concluding Remarks

Dec 21, 2005 HEPAP Accel Research Subpanel 24

Accelerator Research at SLAC

Accelerator research at SLAC is relevant to high energy physics with research

• Supporting operating accelerators
• Designing the International Linear Collider
• Exploring the technology and physics for accelerators in

the future Past accomplishments have been crucial in defining high energy physics today - storage rings and linear collider The research includes theory, simulation, experiment, and technology development.

• The results support accelerators that are centerpieces for
• ther sciences. For example the LCLS.

Collaboration and education are vital aspects of our work.

• We work hand-in-hand with scientists from other labs and

universities

• Education of students from collaborating institutions and

from Stanford

Chris Barnes Sho Wang & Chris Clayton Caolionn O’Connell