177 research outputs found
Laser acceleration of protons from near critical density targets for application to radiation therapy
Laser accelerated protons can be a complimentary source for treatment of
oncological diseases to the existing hadron therapy facilities. We demonstrate
how the protons, accelerated from near-critical density plasmas by laser pulses
having relatively small power, reach energies which may be of interest for
medical applications. When an intense laser pulse interacts with near-critical
density plasma it makes a channel both in the electron and then in the ion
density. The propagation of a laser pulse through such a self-generated channel
is connected with the acceleration of electrons in the wake of a laser pulse
and generation of strong moving electric and magnetic fields in the propagation
channel. Upon exiting the plasma the magnetic field generates a quasi-static
electric field that accelerates and collimates ions from a thin filament formed
in the propagation channel. Two-dimensional Particle-in-Cell simulations show
that a 100 TW laser pulse tightly focused on a near-critical density target is
able to accelerate protons up to energy of 250 MeV. Scaling laws and optimal
conditions for proton acceleration are established considering the energy
depletion of the laser pulse.Comment: 25 pages, 8 figure
Laser-driven high-power X- and gamma-ray ultra-short pulse source
A novel ultra-bright high-intensity source of X-ray and gamma radiation is
suggested. It is based on the double Doppler effect, where a relativistic
flying mirror reflects a counter-propagating electromagnetic radiation causing
its frequency multiplication and intensification, and on the inverse double
Doppler effect, where the mirror acquires energy from an ultra-intense
co-propagating electromagnetic wave. The role of the flying mirror is played by
a high-density thin plasma slab accelerating in the radiation pressure dominant
regime. Frequencies of high harmonics generated at the flying mirror by a
relativistically strong counter-propagating radiation undergo multiplication
with the same factor as the fundamental frequency of the reflected radiation,
approximately equal to the quadruple of the square of the mirror Lorentz
factor.Comment: 8 pages, 5 figures. Presented at the ELI Workshop and School on
"Fundamental Physics with Ultra-High Fields" 29.09.-02.10.2008, in
Frauenworth Monastery, Bavaria, German
On the breaking of a plasma wave in a thermal plasma: I. The structure of the density singularity
The structure of the singularity that is formed in a relativistically large
amplitude plasma wave close to the wavebreaking limit is found by using a
simple waterbag electron distribution function. The electron density
distribution in the breaking wave has a typical "peakon" form. The maximum
value of the electric field in a thermal breaking plasma is obtained and
compared to the cold plasma limit. The results of computer simulations for
different initial electron distribution functions are in agreement with the
theoretical conclusions.Comment: 21 pages, 12 figure
Deconvolution of multi-Boltzmann x-ray distribution from linear absorption spectrometer via analytical parameter reduction
Accurate characterization of incident radiation is a fundamental challenge for diagnostic design. Herein, we present an efficient spectral analysis routine that is able to characterize multiple components within the spectral emission by analytically reducing the number of parameters. The technique is presented alongside the design of a hard x-ray linear absorption spectrometer using the example of multiple Boltzmann-like spectral distributions; however, it is generally applicable to all absorption based spectrometer designs and can be adapted to any incident spectral shape. This routine is demonstrated to be tolerable to experimental noise and suitable for real-time data processing at multi-Hz repetition rates
- …