Phase Helium Flow Research Articles

Thermal hydraulic analysis of two phase helium flow through hydro formed cryopanel

In cryo-sorption cryopump developed at Institute for Plasma Research (IPR), hydro formed cryopanels are cooled down to 4.5K to adsorb hydrogen isotopes and helium gas. These panels are coated with activated carbon. To maintain continuous high pumping speed, panels require frequent regeneration to remove adsorbed gases. Regeneration comprises of two modes of operation, cool down from 300K to 4.5K and warm up from 4.5K to 100–300K. Thermal hydraulic characteristics were studied involving two phase flow of helium through a hydro formed cryopanel of size 500mm (l) ×100mm (w) with a sheet thickness of 1.5mm. Cool down time and transient parameters of two phase helium flow rate were estimated at real time operating conditions. The results are assessed and show good agreement with experiments.

Critical mechanical structure of superconducting high current coils for fast ramped accelerator magnets with high repetition rates in long term operation

The heavy ion synchrotron SIS100 is the core component of the Facility for Antiproton and Ion Research (FAIR) currently under construction at GSI in Darmstadt. It is rapidly cycled with a ramp rate of 4 T/s up to 2 T maximum field and a repetition frequency of 1 Hz. The superconducting coils of the Nuclotron-type magnets utilise a hollow cable cooled with a forced two phase helium flow. These coils must operate reliably over a period of at least 20 years and thus survive 2 · 10 load cycles. Intensive R&D is necessary to find the optimal solution preventing any possible damage of the coils by the fast pulsing loads over the life time taking into account the complex fine structure of the cable and coil designs as well as its sensitive influence on the field quality, AC loss generation and quench protection. We used FEM codes to analyse critical aspects of various design options and had manufactured coils for detailed mechanical tests. These tests on samples extracted from the coil are: thermal expansion measurements in all three directions on the cable package itself and its composite elements, compression tests and investigation of the Inter Laminar Shear Stress (ILSS). The stress strain behaviour of the cable package was measured along the transversal direction; the most important one to sustain the cycling load by Lorentz forces. A second sample was fatigue tested. Successful integral operation test results for the coil mechanics have been obtained within our first experimental runs on the prototype dipole magnets already started at GSI in the end of 2008.

Analysis of coupled electromagnetic-thermal effects in superconducting accelerator magnets

FAIR will built 5 magnet rings including two superconducting synchotrons. The SIS100 is the core component of the facility and will be equipped with 2 Tesla dipole magnets pulsed with 4 Tesla/s. The cable of the magnet coils is made of a hollow NbTi composite cable of about 7 mm outer diameter, cooled with two phase helium flow at 4.5 K. We calculate the heat load, the eddy and the hysteresis losses, investigate the impact of the ramping on the magnetic field, on the safety margin of the conductor and the required cooling for all different elements of the magnet including: the coil, the yoke, the bus bars and the beam pipe. This analysis is based on properties measured at cryogenic temperatures and fine detailed FEM models.

Finite element calculations on detailed 3D models for the superferric main magnets of the FAIR SIS100 synchrotron

The synchrotron SIS100 is one of the two basic accelerators of the future Facility for Antiproton and Ion Research (FAIR) at GSI in Darmstadt. This accelerator should provide high intensity U28+ and proton beams with a pulse repetition rate of 1 Hz (i.e. a ramp rate of 4 T/s). The magnetic system of the accelerator uses superferric 2.1 T dipoles of about 3 m length and 32 T/m quadrupoles of about 1 m length. The magnet coils are made of a hollow tube cable wrapped with Cu/NbTi composite wire cooled with two phase helium flow at 4.5 K. The bore dimensions were defined to 130 × 60 mm for the dipole and 135 × 65 mm for the quadrupole. We present the developed ANSYS models for different important aspects: AC loss, magnetic field quality and mechanical stability. Preliminary studies verified the approaches and these models were applied to calculate the effects for the coil, the yoke and the beam pipe structures. We outline further steps to fully describe the SIS100 magnets including mechanical and thermal properties.

Mechanical Coil Structure of the FAIR SIS 100 Magnets

The SIS 100 magnets of the Nuclotron-type are fast- pulsed superferric cold iron magnets. The dipole coil is a double layer saddle-shaped coil with 16 turns. The cable is a hollow tube NbTi composite cable of about 7.2 mm outer diameter, cooled with two phase helium flow at 4.5 K. A 2D structural analysis of the dipole cross section has been performed to determine the stress levels in the components of the coil package and to suggest an appropriate support structure for the conductor. Different design proposals with the focus on limiting stress in the CuNi cooling tubes and on feasibility of industrial manufacturing procedures have been conceived and analysed. The chosen coil support structure (substrate or comb), together with new insulation and modification of the winding scheme, seems to be an appropriate way to stabilize the coil better and offers important advantages like precise positioning of the conductor, more uniform distribution of loads on the CuNi tubes, an easier winding process on a guiding support, and simplified production procedures. Samples of the new coil structure were produced and tested. The obtained results are presented and discussed.

Status of the Design of a Full Length Superferric Dipole and Quadrupole Magnets for the FAIR SIS 100 Synchrotron

The synchrotron SIS100 is one of the two basic accelerators of the future Facility for Antiproton and Ion Research (FAIR) at GSI in Darmstadt. The SIS100 should provide acceleration of high intensity U <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">28+</sup> and proton beams for 0.5 s, with a pulse repetition rate of 0.6 Hz. In the accelerator magnetic system superferric 2 T dipoles of about 3 m length and 32 T/m quadrupoles of about 1 m length will be used. The magnet coils are made from hollow NbTi composite cable cooled with two phase helium flow at 4.5 K. The lattice comprises 108 dipoles and 168 quadrupoles. The elliptic beam pipe inner dimensions have been fixed at 130 times 60 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> for the dipole and 135 times 65 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> for the quadrupole. Both the dipole and quadrupole design approaches are based on improved versions of the original Nuclotron fast-cycling magnets and provide significantly less AC loss at 4.5 K, better quality of the magnetic field, and a higher long-term mechanical stability of the magnet coils. The results are based on the investigation of 1.4 m dipole and 0.4 m quadrupole Nuclotron-type magnet models. The status of the new magnets design and its manufacturing are presented. Essential features and new results are discussed.

Superferric model dipole magnet with the yoke at 80 K for the GSI future fast cycling synchrotron

Experimental data of a fast cycling (f=1 Hz) 2T dipole magnet based on a superconducting NbTi multi filament hollow cable cooled with forced two phase helium flow at T=4.5K and iron yoke at T=80 K are presented. A new magnet design is proposed. The magnet yoke made of laminated steel consists of two parts: the internal smaller part has close mechanical and thermal contact with the coil while the outer part is separated from the cold mass with a gap of 1 mm and cooled with liquid nitrogen.