Generation of collimated beams of relativistic ions in laser-plasma interactions (original) (raw)
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High density collimated beams of relativistic ions produced by petawatt laser pulses in plasmas
Physical Review E, 2000
Under optimal interaction conditions ions can be accelerated up to relativistic energies by a petawatt laser pulse in both underdense and overdense plasmas. Two-dimensional particle in cell simulations show that the laser pulse drills a channel through an underdense plasma slab due to relativistic self-focusing. Both ions and electrons are accelerated in the head region of the channel. However, ion acceleration is more effective at the end of the slab. Here electrons from the channel expand in vacuum and are followed by the ions dragged by the Coulomb force arising from charge separation. A similar mechanism of ion acceleration occurs when a superintense laser pulse interacts with a thin slab of overdense plasma and the pulse ponderomotive pressure moves all the electrons away from a finite-diameter spot.
Collimated Multi-MeV Ion Beams from High-Intensity Laser Interactions with Underdense Plasma
Physical Review Letters, 2006
A beam of multi-MeV helium ions has been observed from the interaction of a short-pulse highintensity laser pulse with underdense helium plasma. The ion beam was found to have a maximum energy for He 2 of 40 3 ÿ8 MeV and was directional along the laser propagation path, with the highest energy ions being collimated to a cone of less than 10 . 2D particle-in-cell simulations show that the ions are accelerated by a sheath electric field that is produced at the back of the gas target. This electric field is generated by transfer of laser energy to a hot electron beam, which exits the target generating large spacecharge fields normal to its boundary.
Coulomb-Driven Energy Boost of Heavy Ions for Laser-Plasma Acceleration
Physical Review Letters, 2015
An unprecedented increase of kinetic energy of laser accelerated heavy ions is demonstrated. Ultra thin gold foils have been irradiated by an ultra short laser pulse at a peak intensity of 8×10 19 W/cm 2. Highly charged gold ions with kinetic energies up to > 200 MeV and a bandwidth limited energy distribution have been reached by using 1.3 Joule laser energy on target. 1D and 2D Particle in Cell simulations show how a spatial dependence on the ions ionization leads to an enhancement of the accelerating electrical field. Our theoretical model considers a spatial distribution of the ionization inside the thin target leading to a field enhancement for the heavy ions by Coulomb explosion. It is capable of explaining the energy boost of highly charged ions, enabling a higher efficiency for the laser driven heavy ion acceleration.
It is demonstated experimentally that the presence of a long-pulse laser created backplasma on the target backside can focus the relativistic electrons produced by short-pulse laser interaction with the front of a solid target. Comparison to that without the backplasma, the number density of the fast electrons is increased by one order of magnitude and their divergence angle is reduced five fold. The effect can be attributed to the absence of the backside sheath electric field and the collimation effect of the megagauss baroclinic magnetic field there.
Pondermotive acceleration of ions by relativistically self-focused high-intensity short pulse laser
Proceedings of the 1999 Particle Accelerator Conference (Cat. No.99CH36366), 1999
Wc report on llic observation of Iiigli energy ioiis with ctiergics up to 1 MeV accclcralcd pondcrmotivcly hy a relativistically self-focuscd iiitcnsc 5 TW, 400 Cs laser IJlllSC in a supersonic He gas .jct 011 the distance nf a laser spol size. Probing inlcrlerornctry was used ki ohscrvc ciIi-iixib clcctmn-ion cavitation followcd by the plasma expansion with 21 high radial velocity of -3.8 . 10' cinls. IJsiiig tlic nuclcar lrack detcclor CK-39, wc confirmed that t l~c ions arc prclcrcntially accelerated i n the radial direction and the total cncrgy i n high cncrgy ions i s about 1 %, of the laser cncrgy. I)eveliipcd kinetic miidcling Iiriividcs a rcasoaahlc dcscripliiin of B plasma channcl forinatiiin and ion :icecleration.
Laser and Particle Beams, 2004
The mechanism of electron acceleration by intense laser pulse interacting with an underdense plasma layer is examined by one-dimensional particle-in-cell (1D-PIC) simulations. The standard dephasing limit and the electron acceleration process are discussed briefly. A new phenomenon, of short high-quality, well-collimated return relativistic electron beam with thermal energy spread, is observed in the direction opposite to laser propagation. The process of the electron beam formation, its characteristics, and the time-history in x and px space for test electrons in the beam, are analyzed and exposed clearly. Finally, an estimate for the maximum electron energy appears in a good agreement with simulation results.
Review of physics and applications of relativistic plasmas driven by ultra-intense lasers
Physics of Plasmas, 2001
As tabletop lasers continue to reach record levels of peak power, the interaction of light with matter has crossed a new threshold, in which plasma electrons at the laser focus oscillate at relativistic velocities. The highest forces ever exerted by light have been used to accelerate beams of electrons and protons to energies of a million volts in distances of only microns. Not only is this acceleration gradient up to a thousand times greater than in radio-frequency-based sources, but the transverse emittance of the particle beams is comparable or lower. Additionally, laser-based accelerators have been demonstrated to work at a repetition rate of 10 Hz, an improvement of a factor of 1000 over their best performance of just a couple of years ago. Anticipated improvements in energy spread may allow these novel compact laser-based radiation sources to be useful someday for cancer radiotherapy and as injectors into conventional accelerators, which are critical tools for x-ray and nuclear physics research. They might also be used as a spark to ignite controlled thermonuclear fusion. The ultrashort pulse duration of these particle bursts and the x rays they can produce, hold great promise as well to resolve chemical, biological or physical reactions on ultrafast ͑femtosecond͒ time scales and on the spatial scale of atoms. Even laser-accelerated protons are soon expected to become relativistic. The dense electron-positron plasmas and vast array of nuclear reactions predicted to occur in this case might even help bring astrophysical phenomena down to Earth, into university laboratories. This paper reviews the many recent advances in this emerging discipline, called high-field science. new field of physics, known as high-field science. It is not intended to be comprehensive, but rather to be restricted to a discussion of some of the highlights, mainly over the last 5 years, in the relativistic regime of laser-plasma interactions. Several reviews have already been published on highintensity laser development and applications, 2-4 relativistic nonlinear optics, 4,5 laser accelerators, 6 and intense laserplasma interactions. The paper is organized as follows. A brief basic theoretical overview of relativistic laser-plasmas interactions, with references only to early work, is presented in Sec. II. Recent results and references to more recent theoretical and numerical work are discussed in Sec. III A; experimental results are presented in Sec. III B. Prospects and applications are reviewed in Sec. IV.
A new scheme is proposed for proton and light-ion acceleration to relativistic energies by superstrong laser radiation interacting with a structured plasma target. The proposal consists in the use of two-component targets consisting of heavy and light ions, where an ambipolar field is formed under the action of the ponderomotive force of incident radiation, and, in contrast to the traditional schemes, acceleration starts from the front boundary of the layer. It is shown that, for the optimized target parameters, monoenergetic GeV ion beams can be produced for radiation pulse intensities on the order of 10^21–10^22 W/cm^2.
Czechoslovak Journal of Physics, 2004
The basic features of generation of ion beams of ultrahigh (> 10 9 A/cm 2) current densities by the skin-layer subrelativistic interaction of a short (≤ 1 ps) laser pulse with an inhomogeneous plasma layer are studied with the use of a two-fluid hydrodynamic 1-D computer code. The calculations performed for pico-and subpicosecond 1.05-μm laser pulses of intensity ∼ 10 16 ÷ 10 17 W/cm 2 confirm that non-linear ponderomotive forces induced by the laser pulse accelerate two thin (a few μm) plasma blocks of current densities in the range of 10 9 ÷ 10 11 A/cm 2 , propagating in forward and backward directions. The effect of initial plasma density gradient as well as the laser intensity and the pulse duration on characteristics of ion beams is demonstrated and discussed.