FACET-II Facility Overview and Plasma Wakefield ...€¦ · E200: High-Efficiency Acceleration of an Electron Bunch in a Plasma Wakefield Accelerator 12 V) x (mm) No Plasma ON Plasma

FACET-II CD-1 Review, October 27-28, 2015

FACET-II Facility Overview and Plasma Wakefield Acceleration ProgramV. Yakimenko SLAC

LDRS, December 14, 2015

FACET-II, LDRS , V. Yakimenko, December 2015

The Scale for a TeV Linear Collider

31 km

Today’s technology LC – a 31km tunnel:

Plasma Wakefield Technology LC:

The Luminosity Challenge:

4 km

2


Livingston Plot Illustrates the Moore’s Law for Accelerators

3

LHC

Tevatron

LEP-II

SLCHERAStandard Model

The Livingston curve shows the exponential growth in CM energy that has come from new accelerator physics & technology


What is a Plasma Wakefield Accelerator?

4

~1 mm~1m

Want to change from breakdown limited metal structures…

…to plasma structures based on plasma waves that support very large

fields

Simultaneously accelerates and focuses electron beams with fields that are thousands of times stronger than conventional accelerators.

Plasma waves can be excited by

intense laser pulses or particle beams


Plasma Wakefield Acceleration: High Gradients

5

GeV/m: The unit of measure for PWFA

QuickPIC (UCLA) simulation for FACET beam and plasma parameters:


From Conception to Experiment

6

eEz > 50 GeV/m



7

~1 mm~1m



fields






8

~1 mm~1m



fields





Plasma Wakefield Acceleration: High Efficiency

9

Beam loading: The process we use to extract energy from the wake.

The presence of witness electrons “flattens” the Ez field.


Two-Bunch Beam Generation

10

1. Disperse2. Chop

3. Compress4. Accelerate

5. Diagnose

1 2 3 45


Collimation System Shapes Longitudinal Phase Space

for Electron AND Positron Beams

X-band Transverse Deflecting Cavity

11

1.00

90°

Position Along Bunch [mm]Mom

entu

m S

prea

d [%

]N

umbe

r of e

lect

rons

Simulation of Collimated Longitudinal Phase Space

FACET experience has shown that once we have fully compressed beams, small changes to the accelerator result in two bunches for PWFA


E200: High-Efficiency Acceleration of an Electron Bunch in a Plasma Wakefield Accelerator

12

E (G

eV)

x (mm)

Plasma ONNo Plasma

2 GeV Energy Gain ~2% dE/E

~30% efficiencyNature 515, 92-95(November 2014)

Focusing on further optimization at FACET (longer plasma length) Push on beam quality with photo-injector beam at FACET-II

26 GeV

9 GeV Energy Gain

PPCF 9 GeV Paper 7

Figure 1. (a) and (c) show the energetically dispersed transverse charge density profileof the highest peak energy shot from the data set as observed on the wide-field of view(FOV) Cherenkov screen and the Lanex screen, respectively. The left-axis displays theenergy calibration of the screen, and the right and bottom axes display the physicalsize of the beam on the screen. The color axis corresponds to the charge density inunits of pC/mm2, represented on a linear scale. The horizontal lines represent centroidenergy (red), the peak energy (solid black), and the values corresponding to the rmsenergy spread about the peak energy (dashed black). All of these values were calculatedfor the Cherenkov screen shown in (a). (b) and (d) show the horizontally integratedspectral charge density profiles from (a) and (c), respectively.

Table 1. Statistical analysis of accelerated beam spectra, including the standarddeviation (s.d.) of each measured quantity. Values are given for calculation techniquesusing both the centroid energy and spectral peak energy.

Measured Quantity Centroid Energy Spectral Peak Energy

Mean Energy Gain 4.7 GeV (1.1 GeV s.d.) 5.3 GeV (1.4 GeV s.d.)Mean RMS Energy Spread 5.9% (1.3% s.d.) 5.1% (2.3% s.d.)Mean Accelerated Charge 140 pC (55 pC s.d.) 120 pC (47 pC s.d.)

of about five. This di↵erence can be accounted for by the ratio of the length of the two

plasma sources (3.6) and the ratio of accelerated charge (1.6), the combination of which

would lead to a rough estimate of an improvement in energy transfer of about a factor

• Inject two beams into the plasma - One drives the wake, one samples the wake

• Beam loading is key for: - Narrow energy spread & high efficiency


Plasma Wakefield Acceleration: Positrons

13

The field is accelerating behind the pinch in the first bubble. But the field is defocusing in this region.


Extending Plasma Acceleration to Positrons is Not Trivial

14

“Blow-out”

“Suck-in”

No Plasma Plasma

Elec

tron

sPo

sitr

ons

Experiments at SLAC FFTB in 2003 showed that the positron beam was distorted after passing through a low density plasma


Multi-GeV Acceleration of Positrons Demonstrated at FACET and Published in Nature

15

This study is important for plasma afterburner as an energy doubler

Narrow Energy Spread

6 GeV Energy gain per meter

Nature 524, (2015)

New regime: focusing and accelerating region for positrons in the wake of a positron beam


FACET project history

ARRA Funded Project $14.6M + $12M AIP

Primary Goal: • Demonstrate a single-stage high-energy plasma

accelerator for electrons

Timeline: • CD-0 2008 • CD-4 2012, Commissioning (2011) • Experimental program (2012-2016)

A National User Facility: • Externally reviewed experimental program • 150 Users, 25 experiments, 8 months/year operation

Key PWFA Milestones: ✓Mono-energetic e- acceleration ✓High efficiency e- acceleration ✓First high-gradient e+ PWFA • Demonstrate required emittance, energy spread (FY16)

16

The premier R&D facility for PWFA: Only facility capable of e+ acceleration Highest energy beams uniquely enable gradient > 1 GV/m

20GeV, 3nC, 20µm3, e- & e+20GeV, 3nC, 20µm3, e- & e+

LCLS

PPCF 9 GeV Paper 7

Figure 1. (a) and (c) show the energetically dispersed transverse charge density profileof the highest peak energy shot from the data set as observed on the wide-field of view(FOV) Cherenkov screen and the Lanex screen, respectively. The left-axis displays theenergy calibration of the screen, and the right and bottom axes display the physicalsize of the beam on the screen. The color axis corresponds to the charge density inunits of pC/mm2, represented on a linear scale. The horizontal lines represent centroidenergy (red), the peak energy (solid black), and the values corresponding to the rmsenergy spread about the peak energy (dashed black). All of these values were calculatedfor the Cherenkov screen shown in (a). (b) and (d) show the horizontally integratedspectral charge density profiles from (a) and (c), respectively.

Table 1. Statistical analysis of accelerated beam spectra, including the standarddeviation (s.d.) of each measured quantity. Values are given for calculation techniquesusing both the centroid energy and spectral peak energy.

Measured Quantity Centroid Energy Spectral Peak Energy

Mean Energy Gain 4.7 GeV (1.1 GeV s.d.) 5.3 GeV (1.4 GeV s.d.)Mean RMS Energy Spread 5.9% (1.3% s.d.) 5.1% (2.3% s.d.)Mean Accelerated Charge 140 pC (55 pC s.d.) 120 pC (47 pC s.d.)

of about five. This di↵erence can be accounted for by the ratio of the length of the two

plasma sources (3.6) and the ratio of accelerated charge (1.6), the combination of which

would lead to a rough estimate of an improvement in energy transfer of about a factor

FACET: A National User Facility Based on High-energy Beams and Their Interaction with Plasmas and Lasers

17

THz

Cu @100 GHz

Plasma Wake Imaging

Injection

Ionization

Proposal selection through peer reviewed process like in any other user facility

Crystal Channeling of e+

9 GeV e- PWFA

6 GeV e+ PWFA

Hollow Channel Plasmas

Ultrafast Magnetic Switching

Dielectric Wakefield Accelerators


Development of High-Brightness Electron Sources

18

RF

UVlaser

Electronbeam

Plasma Photoinjectors

• 100 GeV/m

• fs beams, µm size

• Promise orders of magnitude improvement in emittance

• Injection from: TH, Ionization, DDR, CP…

LCLS Style Photoinjector

• 100MeV/m field on cathode

• Laser triggered release

• ps beams - multi-stage compressions & acceleration

- Tricky to maintain beam quality (CSR, microbunching…)


FACET-II Plan

Timeline: • Nov. 2013, FACET-II proposal, Comparative review • CD-0 August 24, 2015 • CD-1 Review Oct. 27-28, 2015 • CD-3A Jun. 2016 • CD-2/3B Dec. 2016 • CD-4 2022 • Experimental program (2019-2026)

Key R&D Milestones: • Staging with witness injector • High brightness beam generation, preservation,

characterization • e+ acceleration in e- driven wakes • Generation of high flux THz and gamma radiation

Three stages: • Photoinjector (e- beam only) FY17-18 • e+ damping ring (e+ or e- beams) FY18-19 • “sailboat” chicane (e+ and e- beams) FY19-20

19

10GeV, 5nC, 10µm3, e- & e+LC

LS-II

FACE

T-II

LCLS

FACET-II will enable research for a broad user community


FACET-IIStageI FY17-18

20

L1(e

- )

L0(e- )

L3(e

- )

L2(e

- )

RFGun

BC2EBC1

W-Chicane

FinalFocus&ExperimentalArea

X-bandLinearizer

Linac-0’

SLAClinactunnel(Sectors10–19)Sector20

• Goal: deliver compressed electron beam to experiments in S20

• Major upgrade: Electron beam photoinjector in Sector 10

• Scope: Injector, Shield wall in S10, X-band linearizer, Bunch Compressors in S11 (BC1) and S14 (BC2), beam diagnostics, upgrade to experimental area


FACET-IIStageII FY18-20

21

• Goal: deliver compressed positron beam to experiments in S20

• Major upgrade: positron damping ring

• Scope: damping ring, positron bunch compressor & return line


L0P

L1(e

- )

L0(e- )

Sector14ReturnLineAcceleration

L3(e

- &e+)

L2(e

- &e+)

RFGun

e+DR

BC2EBC1

W-Chicane


X-bandLinearizer

Linac-0’

BC0PositronProduction&ReturnLine

BC2P


FACET-IIStageIII

22

• Goal: deliver electron and positron beams to experiments in S20

• Major upgrade: Sailboat chicane

• Scope: Sailboat chicane


L0P

L1(e

- )

L0(e- )

Sector14ReturnLineAcceleration

L3(e

- &e+)

L2(e

- &e+)

RFGun

e+DR

BC2EBC1

W-Chicane


X-bandLinearizer

Linac-0’

BC0PositronProduction&ReturnLine

BC2P

SailboatChicane


FACET-II Science Opportunities Workshops

23

• Discuss scientific opportunities • Refine the technical

requirements • Ensure maximum impact at

startup and into the future

• October 12-16, 2015 • Five Workshops • Dual WG Leaders - SLAC & non-SLAC 3

0

FACET-II Briefing January 6, 2015

SLAC Electron Beam Test Facilities 5 MeV to 20 GeV

20 GeVe- & e+

FACET

2-16 GeV& single e-

ESTB

5 MeVASTA

60-120 MeVNLCTA

24

FACET & Test Facilities at SLAChttp://facet.slac.stanford.edu

http://facet.slac.stanford.edu

Documents

FACET-II Facility Overview and Plasma Wakefield ...€¦ · E200: High-Efficiency Acceleration of an Electron Bunch in a Plasma Wakefield Accelerator 12 V) x (mm) No Plasma ON Plasma