Theory

Plasma physics

The interaction of injected electron bunches into plasma channels will be modelled and the evolution of the laser, plasma and electron beam (including their mutual interaction) will be followed. Building on the ALPHA-X theoretical research thus far, both fast specialised models (for rapid parametric studies) and more general purpose (but slower) PIC models will be developed in order to investigate matching of velocities, densities and pulse lengths to optimise energy transfer from the wakefield to the injected electrons.
The generation of radiation from the accelerated electrons will form a significant part of the theoretical and computational effort. In addition, the production of betatron and synchrotron radiation in focusing sections and at plasma density transitions can result in electron energy losses, which modify the electron beam transverse and longitudinal emittance. Even though synchrotron losses in beam transport are not significant at energies less than 1 GeV, they should be accounted for when trying to maintain the brightness of the electron beam.
Plasma undulators will be investigated as a means of generating both incoherent and coherent high-energy radiation. Coherent synchrotron radiation, plasma transition radiation and single particle and collective backscattering will also be investigated. A comparison of photon acceleration models based on wave-kinetic and full particle codes should allow limits to be placed on the validity of the wave-kinetic treatment as well as develop scaling relationships for the highest energy photons possible in a particular parameter regime.

High-field physics

The field intensities provided by next-generation high-power laser facilities, such as the Extreme Light Infrastructure, will enable the study of new physical regimes where quantum effects and radiation reaction play a major role. Accelerated charge particles emit electromagnetic radiation, losing energy and momentum, a phenomenon know as radiation reaction. The inclusion of the self-fields in the particle dynamics presents fundamental physical problems, which are still unsolved and controversial. Radiation reaction, negligible at the intensities provided by currently available technologies, may soon become experimentally measurable, helping to discriminate between alternative theoretical models.

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