Self-focusing, channel formation, and high-energy ion generation in interaction of an intense short laser pulse with a He jet

Abstract

Sarkisov, G.S.; Bychenkov, B. Yu.; Novikov, V.N.; Tikhonchuk, V.T.; Maksimchuk, Anatoly; Chen, Shouyuan; Wagner, R.; Mourou, G.; and Umstadter, Donald, "Self-focusing, channel formation, and high-energy ion generation in interaction of an intense short laser pulse with a He jet" (1999 Using interferometry, we investigate the dynamics of interaction of a relativistically intense 4-TW, 400-fs laser pulse with a He gas jet. We observe a stable plasma channel 1 mm long and less than 30 m in diameter, with a radial gradient of electron density ϳ5ϫ10 22 cm Ϫ4 and with an on-axis electron density approximately ten times less than its maximum value of 8ϫ10 19 cm Ϫ3 . A high radial velocity of the surrounding gas ionization of ϳ3.8ϫ10 8 cm/s has been observed after the channel formation, and it is attributed to the fast ions expelled from the laser channel and propagating radially outward. We developed a kinetic model which describes the plasma channel formation and the subsequent ambient gas excitation and ionization. Comparing the model predictions with the interferometric data, we reconstructed the axial profile of laser channel and on-axis laser intensity. The estimated maximum energy of accelerated ions is about 500 keV, and the total energy of the fast ions is 5% of the laser pulse energy. ͓S1063-651X͑99͒07505-4͔ PACS number͑s͒: 52.40.Nk, 52.75. Di, 52.35.Mw

Laser-triggered ion acceleration and table top isotope production

“…The development of shortpulse high-intensity lasers 2 made it possible to accelerate protons and heavier ions to multi-MeV energies in the interaction of these lasers with solid targets, [3][4][5][6] gas jets, 7 and clusters. 8 It was shown that these accelerated protons can induce nuclear transformations.…”

Some critical remarks about the article “A simple air wedge shearing interferometer for studying exploding wires”

“…The first publication about the shearing air wedge interferometer was done in 1996 2 and it was applied successfully to investigating the Coulomb explosion phenomena [3][4][5] due to interaction of a 400 fs 10 TW laser with a gaseous target, and to other laser plasma and Z-pinch investigations as well. Because the authors of Ref.…”

Developments in relativistic nonlinear optics

“…Energetic ions from underdense plasmas were accelerated by an electrostatic sheath, which was created by charge-displacement. Unlike earlier long-laser-pulse experiments, the displacement was due not to thermal expansion but to ponderomotive blow-out [13,14]. When a helium-gas was used as the target, alpha particles were accelerated to several MeV in the direction orthogonal to the direction of laser propagation and along the direction of the maximum intensity gradient.…”