Faites connaître cette offre !
Reference : UMR9012-SYLPRA0-035
Workplace : ORSAY
Date of publication : Wednesday, October 13, 2021
Type of Contract : FTC Scientist
Contract Period : 24 months
Expected date of employment : 1 January 2022
Proportion of work : Full time
Remuneration : Between 2743 and 3896 euros gross per month depending on experience.
Desired level of education : 5-year university degree
Experience required : Indifferent
The candidate will advance the understanding of the specific physics of energy recovery accelerators (ERLs) and thus contribute to the development of this concept for future large machines. He/she will develop innovative simulation tools for electron beam dynamics for the PERLE (Powerful Energy Recovery Linac for Experiments) project: a multi-turn, high average current ERL based on superconducting radio frequency accelerator cavity technology, designed to validate and explore a wide range of accelerator phenomena in a previously unexplored beam power regime.
In its final configuration, PERLE will deliver a 500MeV electron beam, averaging 20mA in intensity, accelerated over three passes through 801.6MHz accelerator cavities. A conceptual design report (CDR) was published by the collaboration in 2017  for a 1GeV version of PERLE.
The candidate will have the opportunity to evolve in the framework of a very high level international collaboration, coordinated by the IJCLab, gathering today expert partners in ERL design and operation. Within IJCLab, he/she will be a member of the Instrumentation, Manipulation and Beam Physics (BIMP) team of the Accelerator Physics Pole of the laboratory.
 D. Angal-Kalinin, PERLE: Powerful Energy Recovery Linac for Experiments - Conceptual Design Report, https://arxiv.org/abs/1705.08783
For ERLs, the beam dynamics must be rigorously studied. Indeed, the beam properties do not result from an equilibrium condition as in storage rings, but are defined by the electron source and by the manipulation performed (magnetic optics, accelerating fields) on the electron packet during its transport. The challenge is to generate, accelerate and transport a very high density electron beam from the source to the experiment site (interaction zone). The beam is then decelerated, for the energy recovery phase, to the stop by passing through the same electromagnetic elements as for the acceleration (i.e. same mesh). In addition to the complexity of the mesh for a multi-pass recirculator, collective effects dominate the transport in these high current accelerators. Thus, beam manipulations must be implemented at the design stage of the accelerator, taking into account the non-linearities generated at the electron emission source and mitigation strategies. Thus, only numerical simulations from the electron source (start) to the stop (end) via the experimental zone can accurately account for the thresholds of instabilities due to collective effects (single and multi-bunch) and to non-linearities.
In a first step, the candidate will study the non-linearities induced by the magnetic fields, and determine the tolerances of the multipolar fields of the magnets and their specifications on the basis of an existing optical mesh, designed by a member of the collaboration: Jefferson Lab (JLAB), with which frequent interactions are to be expected.
After having fixed the multipolar components, the post-doc will have to evaluate the impact of the fluctuations of the parameters acting on the dynamics of the beams (orbit correction, focusing, chromaticity), and thus rule on the robustness of the magnetic optics. These studies will be carried out in close collaboration with JLAB, as well as the other collaboration partners: CERN, ASTeC-Daresbury and the University of Liverpool.
Close collaboration with the Budker Institute of Nuclear Physics (BINP-Novosibirsk), which is in charge of magnet design, will enable a viable magnet design for the PERLE accelerator, using the results of the post-doc's studies. An ultimate performance simulation with field maps will validate the whole study.
Depending on the progress of the magnetic studies, the candidate will also be able to study the single and multi-bunch effects that will limit the performance of multi-pass accelerators. In ERLs, the long-range wake field of the accelerator cavities acts from one bunch to the other and leads to transverse oscillation of the beam orbit or even to beam loss if the amplitude is too large. The trapping of ions (from the residual vacuum) in the potential of the electron beams thus amplifies the "beam break-up" instability. Taking into account the coupled effect of these two sources of instability therefore makes it possible to refine the instability thresholds of the accelerator.
- Knowledge of the dynamics of charged particle beams.
- Experience in the optical design of particle beams (linear or circular) will be considered an asset.
- Interest in numerical simulation. Knowledge of tools such as MADX, Elegant will be considered an asset.
- Languages: French and English (written, oral)
- Autonomy, organisational skills and accountability.
- Communication and argumentation skills, synthesis and critical analysis.
- Ability to learn and develop skills, flexibility. Adaptability and creativity.
Degree required: PhD in physics, training in accelerator physics will be considered an asset for this position.
Level: beginner accepted and up to three years experience.
The Irène Joliot-Curie Laboratory of Physics of the 2 Infinites (IJCLab) is a Joint Research Unit (UMR) under the supervision of the CNRS (IN2P3), the University of Paris-Saclay and the University of Paris. The laboratory is located on the campus of the University Paris-Saclay in Orsay. The campus is located 20 km south of Paris and is easily accessible by RER in 35 minutes.
IJCLab was created in 2020 from the merger of five units (CSNSM, IMNC, IPN, LAL, LPT). The staff is made up of nearly 560 permanent staff (340 engineers, technicians and administrative staff and 220 researchers and teacher-researchers) and about 200 non-permanent staff, including 120 PhD students. The laboratory's research themes are nuclear physics, high-energy physics, theoretical physics, astroparticles, astrophysics and cosmology, particle accelerators, energy and the environment and health. IJCLab has a very large technical capacity (about 280 IT staff) in all the major areas required to design, develop/implement the experimental set-ups necessary for its scientific activity, as well as the design, development and operation of instruments.
The candidate will be integrated into the Physics, Instrumentation and Beam Manipulation (BIMP) team of the Accelerators Pole under the direction of Luc Perrot. He/she will be supervised by Christelle Bruni, researcher of the team and will also participate in the PERLE collaboration, managed by Walid Kaabi.
The BIMP team is composed of 22 people involved in different areas of accelerator design and associated with projects such as FCC, ThomX, MYRRHA, SPIRAL2, MLL-TRAP...
The PERLE project is part of a collaborative effort between CNRS, CERN, Jefferson Lab (JLAB), Budker Institute of Nuclear Physics (BINP-Novosibirsk), STFC-Daresbury, University of Liverpool and Cornell University.
For this position, specific collaborations are planned with JLAB and BINP-Novosibirsk. The collaborative effort with JLAB will focus on the optimisation of the beam transport network design, magnet specifications and beam dynamics studies, while the collaboration with BINP-Novosibirsk will focus on the design and prototyping of the magnets according to the specifications previously established in the network optimisation phase. The collaboration with BINP-Novosibirsk will take place within the framework of the European H2020 CREMLINplus project (https://cordis.europa.eu/project/id/871072), set up to foster scientific cooperation between the Russian Federation and the European Union in the development and scientific exploitation of large-scale research infrastructures. The position described here is funded by the CREMLINplus programme.
The results of the post-doctoral fellow's work will be published and presented in specialist journals and conferences, as well as in the PERLE Technical Design Report (TDR) that the collaboration plans to publish.
Constraints and risks
No constraint, no risk.
Work assignments in France, Europe and the United States are to be expected.
We talk about it on Twitter!