PAC2013 - List of Authors (Pigeon, J.J.)

Paper	Title	Page
MOPAC41	Laser-Plasma Interaction Studies using Above Critical Density Gas Jet Plasmas and a Multi-TW CO2 Laser	153
	C. Gong, C. Joshi, J.J. Pigeon, S. Tochitsky UCLA, Los Angeles, California, USA
	Funding: This work is supported by DOE Grant DE-FG02-92-ER40727, NSF grant PHY-0936266 at UCLA. CO2 laser-plasma interaction provides a unique parameter space for particle acceleration in a gas jet plasma taking place at a critical plasma density n_cr~ 10¹⁹ cm^-3 and even at higher densities (3-10 n_cr). Here we report the latest results of our study of electron acceleration in a wide range of plasma densities 1-10 n_cr using a multi-TW CO2 laser system at the UCLA Neptune Laboratory. To gain insight into plasma density profile evolution during ~ 100 ps long CO2 laser-plasma interaction, we used laser interferometry with two 1 ps, 532 nm probe pulses separated by 5-100 ps. Electron beams recorded in our experiment had a divergence smaller than 15mrad and good shot-to-shot reproducibility. The knowledge of spatial distribution of accelerated electron beam transported through the overdense gas plasma is critically important for minimizing laser beam filamentation and for understanding influence of other laser-plasma instabilities. This should allow for optimization of CO2 laser driven shock wave acceleration of low-divergence monoenergetic ion beams. The results on correlation between electron and ion acceleration in a hydrogen plasma will also be discussed. Haberberger, et al. 2012 Colissionless shocks in a laser produced plasma generate monoenergetic high energy proton beams. Nat. Phys. 8, 95–99

MOPAC44	Development of a High-repetition Rate TW CO2 Laser Driver for a Compact, Variable Species Ion Source	159
	J.J. Pigeon, C. Joshi, S. Tochitsky UCLA, Los Angeles, California, USA
	Funding: U.S. Department of Energy grant DE-FG03-92ER40727 CO2 laser-driven ion acceleration has been used to generate monoenergetic, MeV ion beams from a gas jet plasma. Studies have been limited to single shot experiments even though optimization of the laser-plasma interaction may only be possible at a high repetition rate. Use of a gas jet is advantageous because it offers debris free interactions at a density around the critical plasma density for 10 μm pulses(10¹⁹ cm^-3) and can be retuned for different ion species. At the UCLA Neptune Laboratory we have upgraded our laser system to run at a high repetition rate. We have demonstrated the amplification of 20 GW, 3 ps, laser pulses at 1 Hz. Final amplification is achieved in a 1atm CO2 laser where the bandwidth for ps pulse amplification is provided via field broadening from the laser pulse itself. However, peak powers on the order of 0.2 TW are required for producing 3 MeV proton beams. An increase in our peak power by a factor of 10 is possible through nonlinear chirping and broadening of these pulses in a gas filled hollow waveguide followed by pulse compression. Here we present our strategy for obtaining 300 mJ, 300 fs CO2 laser pulses for driving a 1-10 Hz laboratory ion source. D.J. Haberberger, et. al., Nature Phys. 8, 95-99 (2012).

Paper

Title

Page

Laser-Plasma Interaction Studies using Above Critical Density Gas Jet Plasmas and a Multi-TW CO2 Laser

153

C. Gong, C. Joshi, J.J. Pigeon, S. Tochitsky
UCLA, Los Angeles, California, USA

Funding: This work is supported by DOE Grant DE-FG02-92-ER40727, NSF grant PHY-0936266 at UCLA.
CO2 laser-plasma interaction provides a unique parameter space for particle acceleration in a gas jet plasma taking place at a critical plasma density n_cr~ 10¹⁹ cm^-3 and even at higher densities (3-10 n_cr). Here we report the latest results of our study of electron acceleration in a wide range of plasma densities 1-10 n_cr using a multi-TW CO2 laser system at the UCLA Neptune Laboratory. To gain insight into plasma density profile evolution during ~ 100 ps long CO2 laser-plasma interaction, we used laser interferometry with two 1 ps, 532 nm probe pulses separated by 5-100 ps. Electron beams recorded in our experiment had a divergence smaller than 15mrad and good shot-to-shot reproducibility. The knowledge of spatial distribution of accelerated electron beam transported through the overdense gas plasma is critically important for minimizing laser beam filamentation and for understanding influence of other laser-plasma instabilities. This should allow for optimization of CO2 laser driven shock wave acceleration of low-divergence monoenergetic ion beams*. The results on correlation between electron and ion acceleration in a hydrogen plasma will also be discussed.
* Haberberger, et al. 2012 Colissionless shocks in a laser produced plasma generate monoenergetic high energy proton beams. Nat. Phys. 8, 95–99

MOPAC44

Development of a High-repetition Rate TW CO2 Laser Driver for a Compact, Variable Species Ion Source

159

J.J. Pigeon, C. Joshi, S. Tochitsky
UCLA, Los Angeles, California, USA

Funding: U.S. Department of Energy grant DE-FG03-92ER40727
CO2 laser-driven ion acceleration has been used to generate monoenergetic, MeV ion beams from a gas jet plasma*. Studies have been limited to single shot experiments even though optimization of the laser-plasma interaction may only be possible at a high repetition rate. Use of a gas jet is advantageous because it offers debris free interactions at a density around the critical plasma density for 10 μm pulses(10¹⁹ cm^-3) and can be retuned for different ion species. At the UCLA Neptune Laboratory we have upgraded our laser system to run at a high repetition rate. We have demonstrated the amplification of 20 GW, 3 ps, laser pulses at 1 Hz. Final amplification is achieved in a 1atm CO2 laser where the bandwidth for ps pulse amplification is provided via field broadening from the laser pulse itself. However, peak powers on the order of 0.2 TW are required for producing 3 MeV proton beams. An increase in our peak power by a factor of 10 is possible through nonlinear chirping and broadening of these pulses in a gas filled hollow waveguide followed by pulse compression. Here we present our strategy for obtaining 300 mJ, 300 fs CO2 laser pulses for driving a 1-10 Hz laboratory ion source.
*D.J. Haberberger, et. al., Nature Phys. 8, 95-99 (2012).