T. Zh. Esirkepov

Oncological hadrontherapy with laser ion accelerators

The use of an intense collimated beam of protons produced by a high-intensity laser pulse interacting with a plasma for the proton treatment of oncological diseases is discussed. The fast proton beam is produced at the target by direct laser acceleration. An appropriately designed double-layer target scheme is proposed in order to achieve high-quality proton beams. The generation of high quality proton beams is proved with particle in cell simulations.

Exact charge conservation scheme for Particle-in-Cell simulation with an arbitrary form-factor

The new method of local electric current density assignment in the Particle-in-Cell code in Cartesian geometry is presented. The method is valid for an arbitrary quasi-particle form-factor assuming that quasi-particle trajectory over time step is a straight line. The method allows one to implement the PIC code without solving Poisson equation. The presented formula for the current density associated with the motion of a single quasi-particle is the unique linear combination of form-factor differences in consistency with the discrete continuity equation. The computation scheme is demonstrated in 2D and 3D.

Energy Increase in Multi-MeV Ion Acceleration in the Interaction of a Short Pulse Laser with a Cluster-Gas Target

We demonstrate generation of 10-20 MeV/u ions with a compact 4 TW laser using a gas target mixed with submicron clusters, corresponding to tenfold increase in the ion energies compared to previous experiments with solid targets. It is inferred that the high energy ions are generated due to formation of a strong dipole vortex structure. The demonstrated method has a potential to construct compact and high repetition rate ion sources for hadron therapy and other applications.

Demonstration of laser-frequency upshift by electron-density modulations in a plasma wakefield.

Since the advent of chirped pulse amplification1 the peak power of lasers has grown dramatically and opened the new branch of high field science, delivering the focused irradiance, electric fields of which drive electrons into the relativistic regime. In a plasma wake wave generated by such a laser, modulations of the electron density naturally and robustly take the shape of paraboloidal dense shells, separated by evacuated regions, moving almost at the speed of light. When we inject another counter-propagating laser pulse, it is partially reflected from the shells, acting as relativistic flying (semi-transparent) mirrors, producing an extremely time-compressed frequency-multiplied pulse which may be focused tightly to the diffraction limit. This is as if the counterstreaming laser pulse bounces off a relativistically swung tennis racket, turning the ball of the laser photons into another ball of coherent X-ray photons but with a form extremely relativistically compressed to attosecond and zeptosecond levels. Here we report the first demonstration of the frequency multiplication detected from the reflection of a weak laser pulse in the region of the wake wave generated by the driver pulse in helium plasma. This leads to the possibility of very strong pulse compression and extreme coherent light intensification. This Relativistic Tennis with photon beams is demonstrated leading to the possibility toward reaching enormous electromagnetic field intensification and finally approaching the Schwinger field, toward which the vacuum nonlinearly warps and eventually breaks, producing electron-positron pairs.

Low-frequency relativistic electromagnetic solitons in collisionless plasmas

A relativistic electromagnetic soliton solution in the model of a one-dimensional, unbounded, cold, collisionless plasma is obtained without using the envelope approximation. The breaking of solitons with over-critical amplitudes is observed. The stability of undercritical solitons and the breaking of overcritical solitons are demonstrated by a particle-in-cell computer simulation.

High energy ions generated by laser driven Coulomb explosion of cluster

Abstract We present an analytical model and three dimensional particle simulations of intense laser interaction with a cluster of overdense plasma. When laser intensity is above a critical value, it blows off all of electrons from the cluster and forms a non-neutral ion cloud. During the Coulomb explosion of the ion cloud, ions acquire their energy. Ion energy spectra are discussed in detail for different densities and sizes of clusters with various laser intensities. It is shown that ultra-fast ions are produced for relatively large clusters, and that the ion energy becomes three times greater than the maximum electrostatic potential energy of the ion cloud. The laser driven Coulomb explosion of a cluster may provide a new high energy ion source.

Interaction of Electromagnetic Waves with Plasma in the Radiation-Dominated Regime

A study is made of the main regimes of interaction of relativistically strong electromagnetic waves with plasma under conditions in which the radiation from particles plays a dominant role. The discussion is focused on such issues as the generation of short electromagnetic pulses in the interaction of laser light with clusters and highly efficient ion acceleration in a thin plasma slab under the action of the ponderomotive pressure of the wave. An approach is developed for generating superintense electromagnetic pulses by means of up-to-date laser devices.

Relativistic laser-matter interaction and relativistic laboratory astrophysics

AbstractThe paper is devoted to the prospects of using the laser radiation interaction with plasmas in the laboratory relativistic astrophysics context. We discuss the dimensionless parameters characterizing the processes in the laser and astrophysical plasmas and emphisize a similarity between the laser and astrophysical plasmas in the ultrarelativistic energy limit. In particular, we address basic mechanisms of the charged particle acceleration, the collisionless shock wave and magnetic reconnection and vortex dynamics properties relevant to the problem of ultrarelativistic particle acceleration.

Controlled electron injection into the wake wave using plasma density inhomogeneity

The electron injection, for the laser wake field accelerator, controlled through the plasma density inhomogeneity is studied on a basis of analytical estimates and two- and three-dimensional particle-in-cell simulations. The injection scheme requires a concordance of the density scale length and laser intensity. It is shown that at a sloping inhomogeneity of plasma the wave breaking produces stronger singularity of the electron density than at a density discontinuity, but develops slower. With the help of simulations for a moderate laser intensity, we demonstrate the optimal plasma density gradient, where the electron injection into the wake wave forms the electron beam with low divergence, small energy spread and high energy.

Generation of collimated beams of relativistic ions in laser-plasma interactions

A method is proposed for generating collimated beams of fast ions in laser-plasma interactions. Two-dimensional and three-dimensional particle-in-cell simulations show that the ponderomotive force expels electrons from the plasma region irradiated by a laser pulse. The ions with unneutralized electric charge that remain in this region are accelerated by Coulomb repulsive forces. The ions are focused by tailoring the target and also as a result of pinching in the magnetic field produced by the electric current of fast ions.