187 research outputs found
The reflectivity of relativistic ultra-thin electron layers
The coherent reflectivity of a dense, relativistic, ultra-thin electron layer
is derived analytically for an obliquely incident probe beam. Results are
obtained by two-fold Lorentz transformation. For the analytical treatment, a
plane uniform electron layer is considered. All electrons move with uniform
velocity under an angle to the normal direction of the plane; such electron
motion corresponds to laser acceleration by direct action of the laser fields,
as it is described in a companion paper. Electron density is chosen high enough
to ensure that many electrons reside in a volume \lambda_R^3, where \lambda_R
is the wavelength of the reflected light in the rest frame of the layer. Under
these conditions, the probe light is back-scattered coherently and is directed
close to the layer normal rather than the direction of electron velocity. An
important consequence is that the Doppler shift is governed by
\gamma_x=(1-(V_x/c)^2)^{-1/2} derived from the electron velocity component V_x
in normal direction rather than the full \gamma-factor of the layer electrons.Comment: 7 pages, 4 figures, submitted to the special issue "Fundamental
Physics with Ultra-High Fields" in The European Physical Journal
Laser beam coupling with capillary discharge plasma for laser wakefield acceleration applications
One of the most robust methods, demonstrated up to date, of accelerating
electron beams by laser-plasma sources is the utilization of plasma channels
generated by the capillary discharges. These channels, i.e., plasma columns
with a minimum density along the laser pulse propagation axis, may optically
guide short laser pulses, thereby increasing the acceleration length, leading
to a more efficient electron acceleration. Although the spatial structure of
the installation is simple in principle, there may be some important effects
caused by the open ends of the capillary, by the supplying channels etc., which
require a detailed 3D modeling of the processes taking place in order to get a
detailed understanding and improve the operation. However, the discharge
plasma, being one of the most crucial components of the laser-plasma
accelerator, is not simulated with the accuracy and resolution required to
advance this promising technology. In the present work, such simulations are
performed using the code MARPLE. First, the process of the capillary filling
with a cold hydrogen before the discharge is fired, through the side supply
channels is simulated. The main goal of this simulation is to get a spatial
distribution of the filling gas in the region near the open ends of the
capillary. A realistic geometry is used for this and the next stage
simulations, including the insulators, the supplying channels as well as the
electrodes. Second, the simulation of the capillary discharge is performed with
the goal to obtain a time-dependent spatial distribution of the electron
density near the open ends of the capillary as well as inside the capillary.
Finally, to evaluate effectiveness of the beam coupling with the channeling
plasma wave guide and electron acceleration, modeling of laser-plasma
interaction was performed with the code INF&RNOComment: 11 pages, 9 figure
A New Type of Plasma Wakefield Accelerator Driven by Magnetowaves
We present a new concept for a plasma wakefield accelerator driven by
magnetowaves (MPWA). This concept was originally proposed as a viable mechanism
for the "cosmic accelerator" that would accelerate cosmic particles to ultra
high energies in the astrophysical setting. Unlike the more familiar Plasma
Wakefield Accelerator (PWFA) and the Laser Wakefield Accelerator (LWFA) where
the drivers, the charged-particle beam and the laser, are independently
existing entities, MPWA invokes the high-frequency and high-speed whistler mode
as the driver, which is a medium wave that cannot exist outside of the plasma.
Aside from the difference in drivers, the underlying mechanism that excites the
plasma wakefield via the ponderomotive potential is common. Our computer
simulations show that under appropriate conditions, the plasma wakefield
maintains very high coherence and can sustain high-gradient acceleration over
many plasma wavelengths. We suggest that in addition to its celestial
application, the MPWA concept can also be of terrestrial utility. A
proof-of-principle experiment on MPWA would benefit both terrestrial and
celestial accelerator concepts.Comment: revtex4, 4 pages, 6 figure
Multi-filament structures in relativistic self-focusing
A simple model is derived to prove the multi-filament structure of
relativistic self-focusing with ultra-intense lasers. Exact analytical
solutions describing the transverse structure of waveguide channels with
electron cavitation, for which both the relativistic and ponderomotive
nonlinearities are taken into account, are presented.Comment: 21 pages, 12 figures, submitted to Physical Review
Carbon nanotube substrates enhance SARS-CoV-2 spike protein ion yields in matrix assisted laser desorption-ionization mass spectrometry
Nanostructured surfaces enhance ion yields in matrix assisted laser
desorption-ionization mass spectrometry (MALDI-MS). The spike protein complex,
S1, is one fingerprint signature of Sars-CoV-2 with a mass of 75 kDa. Here, we
show that MALDI-MS yields of Sars-CoV-2 spike protein ions in the 100 kDa range
are enhanced 50-fold when the matrix-analyte solution is placed on substrates
that are coated with a dense forest of multi-walled carbon nanotubes, compared
to yields from uncoated substrates. Nanostructured substrates can support the
development of mass spectrometry techniques for sensitive pathogen detection
and environmental monitoring
Laser-Plasma Interactions Enabled by Emerging Technologies
An overview from the past and an outlook for the future of fundamental
laser-plasma interactions research enabled by emerging laser systems
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