All-Optical Injection

Donald Umstadter

Supported by the High-Energy Physics Division of the U.S. Department of Energy and the National Science Foundation.

AAC, Santa Fe, NM, 2000

Low-divergence Self-trapped MeV Beam

1010 e-

Electron beam profiles for various laser powers: multiple components

Phys. of Plasmas, 7, 403 (2000).

α = 0.6

α = 0.06

0 10 20 30 40101

102

103

104

105

106

107

numberofelectrons/MeV(a.u.)

electron kinetic energy (MeV)

*

Two-temperature Distribution

Slope of Distribution “Jumps” with Density or Laser Power

Laser Injected Laser Accelerator: LILAC

Various LILAC Concepts• D. Umstadter et al., Phys. Rev. Lett. 76, 2073 (1996).

– Ponderomotive kick w/ or w/o ionization

• E. Esarey et al., Phys. Rev. Lett. 79, 2682 (1997).– Beatwave ponderomotive kick

• B. Rau et al., Phys. Rev. Lett. 78, 3310 (1997).– Half-cycle pulse, sharp density gradient

• R. G. Hemker et al., Phys. Rev. E 57, 5920 (1998). – Colliding wakes

• S.V. Bulanov, Plasma Phys. Rep. 25, 468 (1999).– Sharp density gradient

• C.I. Moore et al., Phys. Rev. Lett. 82, 1688 (1999). – Ionization

150-terawatt Laser Construction.

• Preamplifier and cleaner

• Large aperture high energy (~100mJ) regenerative amplifier

• 15J green pump laser.

Current kHz Laser

1.2 m

Inte

nsity

• Intensity 3x1018 W/cm2

• Pulse Duration 8 to 21 fs

• Pulse Energy 3 mJ (21fs)

• Focal Spot Size 1m

Efocused/Etotal=83%

Summary of Our Experimental Observations

• Electron acceleration in a relativistically self-guided plasma channel

• Electron beam: = 1°, mm-mrad• Multiple electron beam components explained• Relativistic filamentation and electron

acceleration w/o significant Raman scatter• Proton Acceleration by vacuum heating• Measured acceleration gradients

– 2 GeV/cm (108 A/cm2)