Cryogenic Design of the 43 T LNCMI Grenoble Hybrid Magnet

AbstractThe association of two inner resistive coils (Polyhelix and Bitter) producing 34.5 T with an outer NbTi superconducting coil producing 8.5 T to obtain a 43 T hybrid magnet is a technical challenge. Accidental failure modes leading to complex electromagnetic behaviors and large transient dynamical forces should be anticipated. These considerations lead to a reinforced design and a thermo-hydraulic strategy to limit the overpressure. The cryostat has been designed with innovative thermo-mechanical supports sustaining the coil at 1.8 K-1200 hPa and the eddy current shield at 30 K, both being possibly overloaded by high dynamic forces in the worst accidental failure case

A 60 GHz electron cyclotron resonance ion source for pulsed radioactive ion beam production

TUCO-A03International audienceElectron Cyclotron Resonance Ion Sources (ECRIS) are very efficient to produce continuous and pulsed ion beams. The ECRIS scaling laws show that the plasma density increases as the square of the microwave frequency. Consequently, the efficiency, the average charge of the ionic charge state distribution and the extracted currents increase as well. LPSC is developing a 60 GHz pulsed ion source prototype. In order to have efficient ionization, the ion source volume has to be small, and due to the frequency value, the magnetic field has to be high (6 T at the injection, 3 T at the extraction, a closed surface with |B| = 2.1 T and a magnetic mirror of 4 T). The generation of the high magnetic field requires the use of helix techniques developed at GHMFL. As a first approach, a cusp structure has been chosen. 2D and 3D simulations were used to define the geometry of the helixes. Calculus has shown that it is necessary to use 2 groups of 2 coaxial helixes. An aluminum helix prototype has been machined to test at low current density the accuracy of the calculations. The axial magnetic field of the prototype was measured and results are in very good agreement with the numerical values

A 60 GHz electron cyclotron resonance ion source for pulsed radioactive ion beam production

TUCO-A03International audienceElectron Cyclotron Resonance Ion Sources (ECRIS) are very efficient to produce continuous and pulsed ion beams. The ECRIS scaling laws show that the plasma density increases as the square of the microwave frequency. Consequently, the efficiency, the average charge of the ionic charge state distribution and the extracted currents increase as well. LPSC is developing a 60 GHz pulsed ion source prototype. In order to have efficient ionization, the ion source volume has to be small, and due to the frequency value, the magnetic field has to be high (6 T at the injection, 3 T at the extraction, a closed surface with |B| = 2.1 T and a magnetic mirror of 4 T). The generation of the high magnetic field requires the use of helix techniques developed at GHMFL. As a first approach, a cusp structure has been chosen. 2D and 3D simulations were used to define the geometry of the helixes. Calculus has shown that it is necessary to use 2 groups of 2 coaxial helixes. An aluminum helix prototype has been machined to test at low current density the accuracy of the calculations. The axial magnetic field of the prototype was measured and results are in very good agreement with the numerical values