Kaikki aineistot
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A project is underway for constructing a new 18 GHz ECR ion source HIISI at University of Jyväskylä. An innovative plasma chamber structure with grooves at magnetic poles for larger chamber radius at poles. The hexapole will be refridgerated to sub-zero temperatures to boost the coercivity and the remanence of the permanent magnet material and to allow the use of high remanence, low intrinsic coersivity permanent magnet materials. The hexapole structure is insulated from high temperature solenoid coils and plasma chamber by vacuum. The thermal design of the structure has been made using a thermal diffusion code taking in account radiative, conductive and convective heat transfer processes. The heat flux distribution from plasma has been estimated using electron trajectory simulations. The electron simulations are verified by comparing the distribution to plasma chamber patterns from 14 GHz ECR. Thermal design efforts are presented together with an analysis of the demagnetizing H-field in the permanent magnets.
At the end of 2013 the Academy of Finland granted an infrastructure funding for the JYFL Accelerator Laboratory in order to increase beam intensities for the international user community. The primary objective is to construct a new high performance ECR ion source, HIISI (Heavy Ion Ion Source Injector), for the K130 cyclotron. Using room temperature magnets the HIISI has been designed to produce about the same magnetic field configuration as the superconducting ECRIS SUSI at NSCL/MSU for 18 GHz operation. An innovative structure will be used to maximize the radial confinement and demagnetization safety margin of the permanent magnets. The sextupole magnet is separated and insulated from the plasma chamber providing two advantages: 1) the permanent magnet can be cooled down to -10˚C to increase its coercivity and 2) at the same time to reach slightly higher radial field on the inner surface of the plasma chamber. Comprehensive simulations were performed with the radial heat load to analyse and address all the heat loads and temperature distribution on the permanent magnet. This information is crucial to define the maximum plasma heating power and the grade of the permanent magnets. In this article the magnetic field design of HIISI and detailed innovative scheme for sextupole magnet will be presented.
Several ion source related research and development projects are in progress at the Department of Physics, University of Jyväskylä (JYFL). The work can be divided into investigation of the ion sourceplasma and development of ion sources,ion beams, and diagnostics. The investigation covers the Electron Cyclotron Resonance Ion Source (ECRIS) plasma instabilities, vacuum ultraviolet (VUV) and visible light emission, photon induced electron emission, and the development of plasma diagnostics. The ion source development covers the work performed for radiofrequency-driven negative ion source, RADIS, beam line upgrade of the JYFL 14 GHz ECRIS, and the development of a new room-temperature-magnet 18 GHz ECRIS, HIISI.