Thermo-mechanical behaviour of a single slice test device for the FRIB high power target F. Pellemoine a,b,n , W. Mittig a , M. Avilov a , D. Ippel a , J. Lenz a , J. Oliva a , I. Silverman c , D. Youchison d , T. Xu a a NSCL—National Superconducting Cyclotron Laboratory, Michigan State University, USA b GANIL—Grand Acce ´le´rateur National d’Ions Lourds, Caen, France c SOREQ Nuclear Research Center, Yavne, Israel d Sandia National Laboratories, Fusion Technology Dept, Albuquerque, New Mexico, USA article info Available online 22 June 2011 Keywords: Electron beam heating Graphite High intensity beam Thermal behaviour High power target abstract One of the major challenges of the FRIB project (Facility for Rare Isotope Beams) at Michigan State University is the design and integration of the production target to produce rare isotope beams via fragmentation reaction. In the most extreme case, a 400 kW uranium beam of 200 MeV/u will be focused in a 1 mm diameter spot, leading to a power density of 60 MW/cm 3 for a C target. Up to 200 kW may be dissipated in the target. A rotating solid carbon disk concept has been selected as the target design approach for all primary beams up to uranium to provide high-power operation. A high rotational speed is necessary to compensate for the high power density. A multi-slice approach allows the evacuation of the large amount of heat deposited by the increase of the radiating area. In the present design study, the multi- slice target device has a diameter of about 30 cm and rotates at about 5000 RPM (revolutions per minute). The first step of the R&D strategy consists in the development and test of a 20 kW single-slice target prototype. This single disk device is designed to accept the same fraction of power as each disk of the final multi-slice target. Critical information on thermal-mechanical properties can be obtained thus at a lower power level than the one of the full device. Different carbon materials were tested. An electron beam of 20 keV was used for the thermal tests. Simulations were performed using the ANSYS code for the thermo-mechanical behaviour of the target, the resulting deformation and the stress profiles of heated graphite disks. Results of the simulations were compared with experimental data. & 2011 Elsevier B.V. All rights reserved. 1. General introduction: overview of FRIB project and R&D for FRIB production target The Facility for Rare Isotope Beams (FRIB) [1,2] at Michigan State University will be a unique facility to understand the fundamental laws that govern the behaviour of nuclei far from stability, and provide a tool of excellence for the nuclear science. FRIB will enable the nuclear science research community to make major advances in the understanding of nature by accessing key rare isotopes that previously only existed in the most violent conditions in the universe. To produce these isotopes in a quantity sufficient for their study, high intensity is a key issue. The FRIB facility is based on a heavy ion linear accelerator with an energy of 200 MeV/u for all ions up to U at a beam power of 400 kW. The facility will have a production target for in-flight production of rare isotopes by fragmentation. A three-stage frag- ment separator will be used to select fast rare isotope beams with high-purity that can be used for fast-beam experiments at about 150 MeV/u. Besides these fast beams, a stopping-beam facility with multi-concept will provide thermalized ion beams for stopped beam experiments or for reacceleration with ReA3 (the new MSU- NSCL Re-Accelerated beam facility) at energies up to 3 MeV/u for uranium, with the possibility for a future energy upgrade. The Experimental Systems at FRIB [3] include the target facilities for rare isotope beam production, the production target, the fragment separator, the beam stopping systems, the re- accelerator systems, and the experimental areas equipped with scientific instrumentation (see Fig. 1). A target concept is needed that is suitable for the heaviest beams, such as uranium, and for the lighter primary beams at FRIB. Important requirements for the ion optics include:  A maximum target extension in the beam-direction of approximately 25 mm together with a small diameter beam Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/nima Nuclear Instruments and Methods in Physics Research A 0168-9002/$ - see front matter & 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.nima.2011.06.010 n Corresponding author at: NSCL—National Superconducting Cyclotron Laboratory, Michigan State University, MSU–NSCL 1, Cyclotron East Lansing, MI 48824-132, USA. Tel.: þ1 517 908 7677; fax: þ1 517 353 5967. E-mail address: pellemoi@frib.msu.edu (F. Pellemoine). Nuclear Instruments and Methods in Physics Research A 655 (2011) 3–9