Staggered undulator X-ray source for low emittance electron storage ring
The European Synchrotron Radiation Facility (ESRF) is a synchrotron light source located in Grenoble, France. It is a 6 GeV electron storage ring based source. Hard X-ray photons are produced by deviating relativistic electrons with periodic magnetic structures called undulators. The production of high energy synchrotron radiation, in the 50 – 100 keV range, is an active R&D topic. Short period undulators must be used to generate these high energy photons efficiently. Undulator periods as short as 14 mm are reached using in-vacuum, low temperature permanent magnet devices.
Undulators with shorter periods can be built using magnetic poles periodically placed in solenoids, so-called staggered undulators. Staggered undulators were studied in the 90’s but have never been installed in storage ring based light sources due to the potentially detrimental effect of the solenoids on the stored beam. A new generation of light sources is being built, led by the construction of the Extremely Brilliant Source (EBS) at the ESRF. The EBS is expected to start at the end of 2019. With this new accelerator, the product of the electron beam size times the electron beam divergence will be divided by a factor 30. In these conditions, the stored electron beam is expected to be less affected the installation of solenoids, and the staggered undulators become a real option for high energy beamlines.
The student will build a computer model of a staggered undulator using the Radia software. This model will be used for exploring the peak field, magnetic period and undulator gap which can be reached with this technology.
The magnetic field within the undulator gap will be used for computing the electric field radiated by the electron beam, using the SRW or the B2E codes. The properties of the X-ray radiation (spectrum, radiation pattern, etc.) of a staggered undulator will be investigated. In particular, the radiation properties of a short period, low deflection undulator will be studied.
The impact of a solenoid on the linear optics of the electron beam transport (coupling, beta functions, etc.) will be studied and correction methods will be considered. The impedance introduced by the undulator will be studied as well.
This study will be completed by the construction and the characterization of a demonstrator. The construction of this prototype will allow the suitable manufacturing method to be defined.
Bulk High Temperature Superconductors (HTS) can potentially increase the field of short period staggered undulators. Preliminary tests will be performed with such materials. The main goal of these tests will be to improve the description of bulk HTS with the Radia software, which is a prerequisite to their use in undulator designs.
Place of Work: mainly at the ESRF in Grenoble (France). Academic follow-up at Ecole Doctorale de Physique of Université Grenoble Alpes (UGA).
Salary: 2378€ gross salary per month
The European Synchrotron, the ESRF, is an international research centre based in Grenoble, France.
Through its innovative engineering, pioneering scientific vision and a strong commitment from its 700 staff members, the ESRF is recognised as one of the top research facilities worldwide. Its particle accelerator produces intense X-ray beams that are used by thousands of scientists each year for experiments in diverse fields such as biology, medicine, environmental sciences, cultural heritage, materials science, and physics.
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