# Presentation: 924354

## L’OASIS Program:

- All-optical accelerators
- Wim Leemans
*l'OASIS Group*
*Center for Beam Physics*
- DoE HEP Review
- Feb. 18-19, 2004

- Outline
- Introduction
- 1 GeV module concept
- Single beam experiments
- Mutibeam experiments: colliding pulse and channeling
- Summary

## Team effort

- D. Schneider (LLNL+LBNL)
- R.Donahue, D. Rodgers, A. Smith (Radiation Detection)
- J. Wurtele(UCB+CBP)
- T. Budinger, J. O'Neil, H. VanBrocklin (CFI/LSD-Radio Isotopes)
- M. Martin, R. Kaindl, M. Carnahan, J. Byrd, J. Singley (ALS/UCB-Coherent IR/THz)
- D. Bruhwihler, D. Dimitrov (TechX-Corp-Simulations)
- J. Cary, R. Giacone (U. Colorado/TechX-Corp-Simulations)
- T. Cowan, H. Ruhl (University of Nevada, Reno)

- Group (Scientists + postdocs + students)
- _Experiment:_ W. Leemans (Group Leader), C. Toth, B. Nagler (Fulbright Fellow), N. Saleh, C. Geddes (UC Berkeley, Hertz Foundation Fellow), K. Nakamura (UTokyo), J. van Tilborg (TUE, NL)
- _Theory:_ E.Esarey (Deputy Group Leader), C. Schroeder, B. Shadwick (1/2), G. Fubiani (Univ. Paris)
- _Techs_: M. Dickinson, D. Syversrud, J. Wallig, N. Ybarrolazza
- Visitors/Postdocs (2003)
- J. Faure (LOA, France)
- D. Auerbach (Princeton)
- M. Walker and F. Wolcott (Summer students)

## Laser wakefield accelerator: principle

- Ultrahigh axial electric fields
-  => Compact electron accelerators
- Plasma wakefields
-     Ez > 10 GV/m, fast waves
- (Conventional RF accelerators
-     Ez ~ 10 MV/m)
- Plasma channel: Guides laser pulse and supports plasma wave

## Program overview

**Physics of and technology for laser driven accelerators**
**Facilities: world-class l’OASIS multi-terawatt laser, radiation shielded caves, control room with computer automated data acquisition**
**Experiment + theory + simulations**
**Educational element FY03 : 4 grads, 2-3 undergrads/year**
**Augmented by collaborations with researchers from SciDAC, AFRD, other divisions (EH&S, ALS, Engineering, MSD, NSD, CFI), other institutions (Cornell, Colorado University, University of Nevada-Reno), companies (TechX-corp)**
**Supports DOE’s HEP mission**
- Website: http://bc1.lbl.gov/CBP_pages/LOASIS/

## Activities/focus of 2003-2004

**Facility upgrade: system improvements and 100 TW upgrade**
**Electron acceleration**
**Controlling accelerator performance**
**Development of 1 GeV module**
** ****Injector: self-modulated + colliding pulse**
** ****Channel: ignitor-heater=> guiding at >10****18**** W/cm****2**** over 15-20 Rayleigh lengths in gas jet**
**Capillary discharge system (Collaboration with Oxford University):3-5 cm**
**Bunch diagnostic: coherent transition radiation**
**Modeling and simulation of non-linear physics**
**Analytic modeling ****(THz, coll.pulse, space charge...)**
**Fluid codes ****(Code development, pump depletion,...)**
**PIC codes ****(with Cary et al., CU Boulder and TechX, Bruhwiler and Dimitrov, TechX, H. Ruhl, University of Nevada Reno)**

## Publications, Presentations, Committees: 2003-2004

- Refereed Journal Publications:    12
- Phys. Rev. and Phys. Rev. Letters:	      3 (+1 submitted)
- Conference Proceedings:            15
- Invited Talks:  		    10
- Professional Service:
-        Chair +Member ICFA Panel on Advanced Accelerators
-        DOE and NSF Review Committees
-        Program Committees

- Summary

## Publications, Presentations, Committees: 2003 - 2004

- Refereed Journal Publications

## Publications, Presentations, Committees: 2003 - 2004

- Refereed Journal Publications - cont’d

## Publications, Presentations, Committees: 2003 - 2004

- Refereed Journal Publications - cont’d

## Publications, Presentations, Committees: 2003 - 2004

- Conference Proceedings

## Publications, Presentations, Committees: 2003 - 2004

- Conference Proceedings - cont’d

## Publications, Presentations, Committees: 2003 - 2004

- Conference Proceedings - cont’d

## Invited presentations 2003-2004

- _Eric Esarey_
- Plenary Talk, OSA Topical Meeting on Applications of High Field and Short Wavelength Sources X, Biarritz, France, October 12 - 15, 2003.
- _Wim Leemans_
- Invited Talk, APS-DPP 2003 Annual Meeting, Albuquerque, NM, October 26-31, 2003
- Plenary Talk, ICFA Laser-Beam Workshop 2003, Oxford UK, 7-11 July 2003.
- Invited Seminars:
- 	 - RPM, LBNL, November 13, 2003
- 	- UCB Seminar 251, November 5, 2003
- 	- Cornell University, April 24, 2003
- _Carl Schroeder_
- Invited Talk, ICFA Workshop on Laser and Plasma Accelerators, Portovenere, Italy, September 11-15, 2003

## Publications, Presentations, Committees: 2003 - 2004

- Professional Service

- _E. Esarey_
- Member of ICFA Panel on Advanced and Novel Accelerators, 2000-2003.
- Program Committee ICFA 3rd International Workshop on Laser - Beams Interactions, Oxford, July 7th -11th 2003.
- Scientific Advisory Committee, Workshop on Laser and Plasma Accelerators, Portovenere, Italy, 9/29-10/3, 2003.
- _W. Leemans_
- Chair of ICFAPanel on Advanced and Novel Accelerators, 2000-2003.
- Program Committee, ICFA 3rd International Workshop on Laser - Beams Interactions, Oxford, July 7th -11th 2003.
- Program Committee, Conference Lasers Electro-Optics (CLEO) 2004
- Scientific Advisory Committee, Int’l Workshop on Laser Plasma Accelerators, Portovenere, Italy, 9/29-10/3, 2003.
- Scientific Advisory and Organizing Committee Advanced Accelerator Concepts Workshop 2004.
- DOE consultant for BNL-HEP review 2003.
- _Cs. Tóth_
- Member  of Review Panel, Basic Research and Higher Education Program of U.S. Civilian Research and Development Foundation (CRDF), 2002-2003.

## Concept: Two stage all-optical accelerator module*

**100 TW class laser system: two stage module**

- Concept: Two stage all-optical accelerator module*

- * A. Reitsma, W. P. Leemans, E. Esarey et al., PRST-AB,5, 051301  (2002)

## Development of GeV laser-plasma module: 

**Few MeV injection, 1 GeV output after 12 cm**

- * A. Reitsma, W. P. Leemans, E. Esarey et al., PRST-AB,5, 051301  (2002)

-  Laser: 40 TW, 80 fs (FWHM)
-  Beam: 100 pC, 30 m (rms), 8 fs (rms)
-  Channel: 12.5 cm, 2.5x1017 cm-3

- Requires L’OASIS upgrade

- Input spectrum

- Output spectrum

## }

- 10 TW Ti:sapphire

- 100 TW Ti:sapphire
- (under construction)

- Shielded target room

- Tool: l’OASIS multi-terawatt laser

_**L’OASIS laser system**_
- _Three main amplifiers (Ti:sapphire,10 Hz):_
- 	- Godzilla:
- 		0.5-0.6 J in 40-50 fs (10-15 TW) ===> main drive beam (to date)
- 	- Chihuahua:
- 		20-50 mJ in 50 fs                        ===> ignitor beam
- 		250-300 mJ in 200-300 ps          ===> heater beam
- 		20-80 mJ in 50 fs                        ===> colliding beam
- 	- 100 TW arm:
- 		3-4 J in 30-40 fs		         ===> under commissioning

- guiding

## Laser wakefield experiments: single drive beam

**L’OASIS LAB**
**800nm Ti-Sapphire**
**10 Hz CPA Laser System**
**50 fs pulses**
**focus: w~6 ********m**
**0.5 J/pulse**
**10-15 TW  **

-  Properties of e-bunch
-  Energy distribution
-  Spatial distribution
-  Bunch duration

-  Electron yield control via laser pulse shape:
-  W.P. Leemans et al., PRL 2002
-  C.B. Schroeder et al., PRE and Phys. Plasmas 2003
-  Radiation from bunches crossing plasma-vacuum
-  W. P. Leemans et al., PRL 2003 and Phys. Plasmas 2004
-  C.B. Schroeder et al., PRE 2004
-  Coherent THz radiation
-  Diagnostic: bunch duration from spectrum 30-50 fs (FWHM)

## Transition radiation from plasma-vacuum boundary serves as bunch diagnostic

-  Used spectral filters to measure energy in 0.3-3 THz and 0.3-30 THz ranges

## Multi-beam wakefield experiments: channels via ignitor-heater and colliding pulse

- S-pol

- P-pol

## Injector concept: Colliding pulse injection

- Normalized potentials

- = plasma wake phase =

## Second phase of colliding pulse: guiding in narrow jet 

- Second phase of colliding pulse: guiding in narrow jet

## Relativistic intensities (> 1018 W/cm2 ) guided at LBNL

- C. Geddes et al., in preparation

- Effect on electron beam ?

## Channeled accelerator produces tighter beams

- 4884881

- 1/15/04
- 4897359

- Effect of Channeling on e-beam
- Beam Spots @ 72 cm

- e-

- Beam Phosphor

- LANEX

- 72cm

- Strong reduction of divergence with channeled beams
- Evaluation including space charge under way
- Charge: 1nC no channel, 10-100pC with channel

- mrad

- mrad

- Unchanneled

- Channeled

## Single beam

- E-beam with laser channeling far superior than unchanneled accelerator

- Detection threshold

## Input laser mode affects channel coupling and electron yield

- 4895506

- 4/15/04
- 4895506

- • Output Mode
- 10% transmitted.
- Iout ~ 3%Iin~3e17

- Case 1: Distorted input mode

- • Thermal loading on grating at 10 Hz operation causes mode distortion. Operation at 1 Hz preserves mode.  Need adaptive optic to correct for10 Hz operation

- • Side Interferometer

- μm

- 4/15/04
- 4895013

- • Output Mode
- 10% transmitted.
- Iout ~ 5%Iin~5e17

- • Side Interferometer

- Case 2: Clean input mode

-  Observe e-beam, gamma rays
-  Large neutron increase over single beam

-  Clean output mode
-  No significant electron output !

- Suppression of self-trapping using plasma channel with clean input laser mode

## Hydrogen capillary discharge system will be used to study long scale length guiding (30-70 mm)

- Pressure balance creates density profile suitable for guiding

-  Collaboration underway

**Nathan**

**Tony**

**Don**

**Joe**

## Summary

-  Ultra-high gradient (10-100 GV/m): tens of MeV in mm-scale length accelerator
-  Femtosecond electron bunches (via coherent THz emission) 
-  High charge yield (multi-nC) but with 100 % energy spread 
-   Laser guiding at relativistic intensities in preformed channels 
-  Guided > 1018 W/cm2 ; channel incoupling controls trapping of electrons
-  %-level energy spread observed for 85 MeV beam 
-  Beams up to 150 MeV observed--70 GV/m gradient
-  Low divergence (mrad-level) 
-  Laser triggered injection experiments underway (FY04)
-  1 GeV module within reach using 1-10 cm channels
-  Collaboration with Oxford University (FY04)
-  Requires equipment funds
-  L’OASIS 100 TW, 10 Hz system coming on-line (FY04)
-  Laser technology key to success (beam stabilizers, adaptive optics etc...)
- Theory status will be described tomorrow (by E. Esarey)