Laser-driven collimated tens-GeV monoenergetic protons from mass-limited target plus preformed channel

Abstract

Proton acceleration by ultra-intense laser pulse irradiating a target with cross-section smaller than the laser spot size and connected to a parabolic density channel is investigated. The target splits the laser into two parallel propagating parts, which snowplow the back-side plasma electrons along their paths, creating two adjacent parallel wakes and an intense return current in the gap between them. The radiation-pressure pre-accelerated target protons trapped in the wake fields now undergo acceleration as well as collimation by the quasistatic wake electrostatic and magnetic fields. Particle-in-cell simulations show that stable long-distance acceleration can be realized, and a 30 fs monoenergetic ion beam of >10 GeV peak energy and <2 divergence can be produced by a circularly polarized laser pulse at an intensity of about 10 22 W/cm 2 . V C 2013 American Institute of Physics. [http://dx

Proton acceleration in underdense plasma by ultraintense Laguerre–Gaussian laser pulse

“…Simultaneously, the witness proton beam is located in the black-dashed box and is confined by the focusing field. The focusing field is similar to the twin bubbles in the previous study [22] but with different generation schemes.…”

“…For the proton acceleration in the wakefield, the acceleration distance that the trapped protons travel before they outrun the bubble, i. e. the dephasing length, which is approximated as π λ ∼ L a n n (1/4 )( / ) dp c 2 0 3/2 [22], is important because it is critical for the final energy of the accelerated protons. The laser pulse depletion length is another important factor, which is decided by the laser duration once the laser intensity and background plasma density are given.…”

Optimization of relativistic laser–ion acceleration

“…It may also become necessary to consider novel methods not discussed here. For example, once the ions move with the speed of light, staged acceleration possibly implementing plasma wake acceleration as used presently to accelerate electrons may provide a more effective means to reach higher energies [109][110][111] . In any case, even with lower output ion energies as compared with conventional accelerators, laseraccelerated ion bunches are still desirable, due to their bunch densities which may be close to solid density.…”

Z-petawatt driven ion beam radiography development.

“…Such energies are well beyond the present capability of laser acceleration. However, computer simulations suggest that future lasers might be able to reach those energies [49]. If 4.5 GeV protons, with ±15° angular spread are injected at (0,-13,-2.7) mm, they indeed generate an image/deflectogram of the field structure, as shown in Figure 19.…”