5 research outputs found
GigaGauss solenoidal magnetic field inside of bubbles excited in under-dense plasma
Magnetic fields have a crucial role in physics at all scales, from
astrophysics to nanoscale phenomena. Large fields, constant or pulsed, allow
investigation of material in extreme conditions, opening up plethora of
practical applications based on ultra-fast process, and studying phenomena
existing only in exotic astro-objects like neutron stars or pulsars. Magnetic
fields are indispensable in particle accelerators, for guiding the relativistic
particles along a curved trajectory and for making them radiate in synchrotron
light sources and in free electron lasers. In the presented paper we propose a
novel and effective method for generating solenoidal quasi-static magnetic
field on the GigaGauss level and beyond, in under-dense plasma, using
screw-shaped high intensity laser pulses. In comparison with already known
techniques which typically rely on interaction with over-dense or solid
targets, where radial or toroidal magnetic field localized at the stationary
target were generated, our method allows to produce gigantic solenoidal fields,
which is co-moving with the driving laser pulse and collinear with accelerated
electrons. The solenoidal field is quasi-stationary in the reference frame of
the laser pulse and can be used for guiding electron beams and providing
synchrotron radiation beam emittance cooling for laser-plasma accelerated
electron and positron beams, opening up novel opportunities for designs of the
light sources, free electron lasers, and high energy colliders based on laser
plasma acceleration.Comment: 15 pages, 9 figures. Main text (without abstract, References and
Appendix): 12 page
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
Thickness of natural contaminant layers on metal surfaces and its effects on laser-driven ion acceleration
In the laser-driven ion acceleration studies, the naturally deposited contaminant layer on the target surface is thought to be a source of energetic ions and protons. Using ellipsometric measurements, we found that the thickness of the surface natural contaminant layer, which cannot be modified without external surface treatment, is on the order of a few nanometers. A conceptual approach is developed where “thick” and “thin” contaminant layer regimes of acceleration are identified and parameterized by the normalized thickness of the contaminant layer. These studies may also help in developing an ion acceleration concept using multilayered targets or through modifications of the target surface