METHOD AND APPARATUS FOR HIGH ENERGY GENERATION AND FOR INDUCING NUCLEAR REACTIONS

A System is provided for generating high-energy particles and for inducing nuclear reactions. The System includes a laser and for emitting a laser beam, an irradiation target for receiving the laser beam and producing high-energy particles, and a Secondary target for receiving the high energy particles, thereby inducing a nuclear reaction. A method is also provided including producing a laser beam of high-intensity with an ultra-short pulse duration, irradiating the laser beam onto an irradiation target in order to ionize the irradiation target and produce a collimated beam of high energy particles, and colliding the collimated beam of high energy particles onto a Secondary target containing a nuclei, thereby inducing a nuclear reaction on the Secondary target

Generation of GeV protons from 1 PW laser interaction with near critical density targets

The propagation of ultra intense laser pulses through matter is connected with the generation of strong moving magnetic fields in the propagation channel as well as the formation of a thin ion filament along the axis of the channel. Upon exiting the plasma the magnetic field displaces the electrons at the back of the target, generating a quasistatic electric field that accelerates and collimates ions from the filament. Two-dimensional Particle-in-Cell simulations show that a 1 PW laser pulse tightly focused on a near-critical density target is able to accelerate protons up to an energy of 1.3 GeV. Scaling laws and optimal conditions for proton acceleration are established considering the energy depletion of the laser pulse.Comment: 26 pages, 8 figure

Accelerating Protons to Therapeutic Energies with Ultra-Intense Ultra-Clean and Ultra-Short Laser Pulses

Proton acceleration by high-intensity laser pulses from ultra-thin foils for hadron therapy is discussed. With the improvement of the laser intensity contrast ratio to 10-11 achieved on Hercules laser at the University of Michigan, it became possible to attain laser-solid interactions at intensities up to 1022 W/cm2 that allows an efficient regime of laser-driven ion acceleration from submicron foils. Particle-In-Cell (PIC) computer simulations of proton acceleration in the Directed Coulomb explosion regime from ultra-thin double-layer (heavy ions / light ions) foils of different thicknesses were performed under the anticipated experimental conditions for Hercules laser with pulse energies from 3 to 15 J, pulse duration of 30 fs at full width half maximum (FWHM), focused to a spot size of 0.8 microns (FWHM). In this regime heavy ions expand predominantly in the direction of laser pulse propagation enhancing the longitudinal charge separation electric field that accelerates light ions. The dependence of the maximum proton energy on the foil thickness has been found and the laser pulse characteristics have been matched with the thickness of the target to ensure the most efficient acceleration. Moreover the proton spectrum demonstrates a peaked structure at high energies, which is required for radiation therapy. 2D PIC simulations show that a 150-500 TW laser pulse is able to accelerate protons up to 100-220 MeV energies.Comment: 26 pages, 6 figure

Quasimonoenergetic electron beams with relativistic energies and ultrashort duration from laser-solid interactions at 0.5 kHz

International audienceWe investigate the production of electron beams from the interaction of relativistically-intense laser pulses with a solid-density SiO2 target in a regime where the laser pulse energy is -mJ and the repetition rate -kHz. The electron beam spatial distribution and spectrum were investigated as a function of the plasma scale length, which was varied by deliberately introducing a moderate-intensity prepulse. At the optimum scale length of λ/2, the electrons are emitted in a collimated beam having a quasimonoenergetic distribution that peaked at -0.8MeV. A highly reproducible structure in the spatial distribution exhibits an evacuation of electrons along the laser specular direction and suggests that the electron beam duration is comparable to that of the laser pulse. Particle-in-cell simulations which are in good agreement with the experimental results offer insights on the acceleration mechanism by the laser field. © 2009 The American Physical Society

Ion acceleration with few cycle relativistic laser pulses from foil targets

Ion acceleration resulting from the interaction of 11 fs laser pulses of ~35 mJ energy with ultrahigh contrast (<10^-10), and 10^19 W/cm^2 peak intensity with foil targets made of various materials and thicknesses at normal (0-degree) and 45-degree laser incidence is investigated. The maximum energy of the protons accelerated from both the rear and front sides of the target was above 1 MeV. A conversion efficiency from laser pulse energy to proton beam is estimated to be as high as ~1.4 % at 45-degree laser incidence using a 51 nm-thick Al target. The excellent laser contrast indicates the predominance of vacuum heating via the Brunels effect as an absorption mechanism involving a tiny pre-plasma of natural origin due to the Gaussian temporal laser pulse shape. Experimental results are in reasonable agreement with theoretical estimates where proton acceleration from the target rear into the forward direction is well explained by a TNSA-like mechanism, while proton acceleration from the target front into the backward direction can be explained by the formation of a charged cavity in a tiny pre-plasma. The exploding Coulomb field from the charged cavity also serves as a source for forward-accelerated ions at thick targets.Comment: 12 pages, 7 figures

METHOD AND APPARATUS FOR HIGH ENERGY GENERATION AND FOR INDUCING NUCLEAR REACTIONS

A System is provided for generating high-energy particles and for inducing nuclear reactions. The System includes a laser and for emitting a laser beam, an irradiation target for receiving the laser beam and producing high-energy particles, and a Secondary target for receiving the high energy particles, thereby inducing a nuclear reaction. A method is also provided including producing a laser beam of high-intensity with an ultra-short pulse duration, irradiating the laser beam onto an irradiation target in order to ionize the irradiation target and produce a collimated beam of high energy particles, and colliding the collimated beam of high energy particles onto a Secondary target containing a nuclei, thereby inducing a nuclear reaction on the Secondary target

Effects of ionization in a laser Wakefield accelerator

Experimental results are presented from studies of the ionization injection process in laser wakefield acceleration using the Hercules laser with laser power up to 100 TW. Gas jet targets consisting of gas mixtures reduced the density threshold required for electron injection and increased the maximum beam charge. Gas mixture targets produced smooth beams even at densities which would produce severe beam breakup in pure He targets and the divergence was found to increase with gas mixture pressure

Effects of ionization in a laser Wakefield accelerator

Experimental results are presented from studies of the ionization injection process in laser wakefield acceleration using the Hercules laser with laser power up to 100 TW. Gas jet targets consisting of gas mixtures reduced the density threshold required for electron injection and increased the maximum beam charge. Gas mixture targets produced smooth beams even at densities which would produce severe beam breakup in pure He targets and the divergence was found to increase with gas mixture pressure