Science and Technology

Técnico Student proposes solution to mitigate plasma instabilities

Mariana Moreira’s work may contribute to solving a problem at an experiment based at CERN.

A research team from Instituto Superior Técnico, in collaboration with the Max Planck Institute for Physics (Germany), published an article in Physical Review Letters that proposes a solution to a problem associated with plasma-based particle acceleration.

In the article “Mitigation of the Onset Hosing in the Linear Regime through Plasma Frequency Detuning”, the researchers propose to solve the instability that can be developed when a particle beam propagates in plasma and is subject to the associated electric fields, which can be extremely strong, resulting in its potential disruption.

The work carried out by Mariana Moreira, PhD student in Physics under the supervision of Jorge Vieira, Técnico professor at the Department of Physics, shows that the centroid oscillation (i.e., the mean transverse position of the particles) of a long beam can be treated as a classical oscillator driven by a harmonic external force (the plasma wakefields) under certain conditions. By controlling the frequency of the external force – which can be achieved by varying the plasma density – it is possible to control the growth of the hosing instability.

Plasma-based particle acceleration can occur under various configurations and regimes. However, the problem of instability persists, as mentioned in the article, explains Mariana Moreira. This discovery may contribute to the resolution of this problem, in the AWAKE experiment based at the European Laboratory for Particle Physics (CERN), which operates in one of these regimes. At a more fundamental level, this work also proposes a new paradigm to explore the interactions between beams (of particles or light) and plasma.

In the near future, the Técnico student is “applying the same paradigm to another instability that would be useful to control”. Her work has left “several potential open avenues for research” such as “what could be discovered by applying this paradigm to other instabilities and regimes?” or “how to explore this discovery in a real and experimental implementation?”.

The idea of plasma-based particle acceleration – which would allow the emergence of much more compact and potentially cheaper accelerators – was first put forward in 1979. Since then, different possibilities of realising the basic concept have multiplied.