Plasma acceleration
The basic concepts of plasma acceleration and its possibilities were originally conceived by Toshiki Tajima and John M. Dawson of UCLA in 1979.
[1] The initial experimental designs for a "wakefield" accelerator were conceived at UCLA by Chandrashekhar J. Joshi et al.[2] The Texas Petawatt laser facility at the University of Texas at Austin accelerated electrons to 2 GeV over about 2 cm (1.6×1021 gn).
[3] This record was broken (by more than twice) in 2014 by the scientists at the BELLA Center at the Lawrence Berkeley National Laboratory, when they produced electron beams up to 4.25 GeV.
It was shown to be able to achieve 400 to 500 times higher energy transfer compared to a general linear accelerator design.
[8] In August 2020 scientists reported the achievement of a milestone in the development of laser-plasma accelerators and demonstrate their longest stable operation of 30 hours.
[9][10][11][12][13] A plasma consists of a fluid of positive and negative charged particles, generally created by heating or photo-ionizing (direct / tunneling / multi-photon / barrier-suppression) a dilute gas.
Under normal conditions the plasma will be macroscopically neutral (or quasi-neutral), an equal mix of electrons and ions in equilibrium.
Here the plasma accelerator science provides the breakthrough to generate, sustain, and exploit the highest fields ever produced in the laboratory.
The acceleration gradient produced by a plasma wake is in the order of the wave breaking field, which is In this equation,
What makes the system useful is the possibility of introducing waves of very high charge separation that propagate through the plasma similar to the traveling-wave concept in the conventional accelerator.
Currently, plasma wakes are excited by appropriately shaped laser pulses or electron bunches.
This forms a full wake of an extremely high longitudinal (accelerating) and transverse (focusing) electric field.
A beam-driven wake can be created by sending a relativistic proton or electron bunch into an appropriate plasma or gas.
If the fields are strong enough, all of the ionized plasma electrons can be removed from the center of the wake: this is known as the "blowout regime".
In the linear regime, plasma electrons aren't completely removed from the center of the wake.
[17] This new scheme offers further improvements in hadrontherapy,[18] fusion fast ignition[19] and sources for fundamental research.
For this reason, so far there exists no perfect theoretical model capable of producing quantitative predictions for the TNSA mechanism.
On the rear face of the target there is a small layer of contaminants (usually light hydrocarbons and water vapor).
In contrast, the maximum field in a plasma is defined by mechanical qualities and turbulence, but is generally several orders of magnitude stronger than with RF accelerators.
The beam-driven plasma wakefield acceleration facility will be built in the INFN National Laboratory of Frascati (LNF) near Rome in Italy.
