Space-charge effects in single-particle dynamics in SOLEIL II

Situated at the heart of the Paris-Saclay cluster, approximately 20 km from Paris, SOLEIL is the French national synchrotron radiation source. In this large research infrastructure, the scientific experiments exploit the light from synchrotron radiation from the infrared to hard X-rays. Since 2008, SOLEIL has been serving many research fields in physics, biology and chemistry with applications in Materials Science, Structural Biology, Pharmaceuticals, Environmental & Earth Sciences and Cultural Heritage. SOLEIL, overseen by the CNRS and the CEA, provides its personnel with a multidisciplinary and internationally renowned working environment.

Type of internship: 2nd year of the Master course

Period and duration: From spring to autumn in the year 2024; 6 months

Tutor(s) of the internship: V. Gubaidulin

Description of the proposed studies:

An electron beam can contain billions of particles that can interact with each other and their environment leading to various collective effects. Collective effects can limit the performance of many large-scale particle accelerator facilities. This study will be focused on the collective effect, namely electomagnetic field of the beam on itself, the so-called space-charge effect. This effect was recently demonstrated to be relevant to light sources [1]. Space-charge effect creates a large spread of oscillation frequencies of particles inside the beam. This can be both beneficial and detrimental to the beam. For example, it can induce periodic crossing of (incoherent) single-particle resonances or (coherent) mode instabilities. Space charge can also alter the optics functions (e.g beta-beating) and directly affect emittance as a defocusing effect. All of these effects are actively studied in the community of hadron synchrotrons. However, in a light source many additional effects exist, namely synchrotron radiation, dual RF system with a harmonic cavity, and a desire to operate with a round beam. These effects can alter the beam dynamics with space-charge. This new parameter regime can lead to a degradation of the beam quality, namely to an increase of the main figure of merit of a light source performance -- transverse beam emittance. The goal of the internship is to evaluate the overall effect of space charge on the SOLEIL II storage ring beam emittance.

Requirements:

• A solid understanding of relativistic mechanics and electromagnetism.

• Basic familiarity with accelerator physics.

• Python programming skills. Project Objectives:

• Investigate the overall impact of space-charge on beam emittance and the choice of a tune working point in a next-generation light source .

• Analyze the interplay between space-charge effect and other factors [2], namely synchrotron radiation, intrabeam scattering and a dual harmonic RF system.

• Contribute to novel research in an unexplored parameter regime. What You’ll Learn: • In-depth knowledge of beam dynamics and space-charge effects in particle accelerators. • Experience in numerical simulations and analytical modeling of complex accelerators. • Hands-on training with high performance computing tools used in accelerator physics.