FT/3-4Rb Superconducting Magnets of SST-1 Tokamak (original) (raw)
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Superconducting Magnets of SST-1 Tokamak
at 20th IAEA Fusion …, 2004
Abstract: Magnet System of SST-1 comprises of sixteen superconducting D-shaped Toroidal Field (TF) coils, nine superconducting Poloidal Field (PF) coils and a pair of resistive PF coils inside the vacuum vessel. TF magnets generate the basic 3.0 T field at the major radius of ...
Quench detection and data acquisition system for SST-1 superconducting magnets
Fusion Engineering and Design, 2005
Superconducting magnet system of steady state superconducting Tokamak (SST-1) shall be operating in a very noisy environment. Presences of high inductive voltages in the magnets during off-normal events like VDE, plasma disruption and PF magnet ramp ups, etc. has made quench detection and data acquisition a challenging task. A hybrid of analog electronic circuits and software-controlled data acquisition system has been developed and tested to safeguard the magnets. This paper will describe the electronic hardware circuits developed for signal conditioning, high voltage suppression, fail-proof quench detection and for noise elimination algorithms and their testing. The SST-1 superconducting magnets will have large number of sensors like voltage taps, Venturi flow meter, strain gages, hall probes, pressure sensors, temperature sensors and displacement transducers. A real time data acquisition system has been designed using VMEbus for monitoring and storing signals from all these sensors and initiating control action in case of offnormal events. The paper will also describe the configuration of the data acquisition system with emphasis on hardware used and the software developed for it.
First Engineering Validation Results of SST-1 TF Magnets System
IEEE Transactions on Applied Superconductivity, 2000
All SST-1 superconducting Toroidal Field (TF) and Poloidal Field (PF) magnets have been refurbished, integrated and assembled onto the SST-1 machine shell in mid of 2012. Fabrication of sub nano-ohm, leak tight DC joints in superconducting magnets winding packs, enhancing the insulation strength in operating conditions and test qualifying all the magnets prior to their integration in SST-1 machine shell were the primary refurbishment aspects. All assembled SST-1 TF magnets in SST-1 machine shell have since been successfully cooled down employing 1.3 kW SST-1 Helium Refrigerator/ Liquefier system maintaining helium leak tightness under all temperature conditions. The TF magnets have experimentally demonstrated thermo-mechanical behavior as per the design as well as excellent flow uniformity amongst various parallel paths. Subsequently, these TF magnets have been increasingly charged so as to create a magnetic field of 1.5 T at the SST-1 major radius of 1.1 m. This is the first occasion, when cable-in-conduit wound toroidal field magnets have been successfully operating with two phase flow in a Tokamak application. The first plasma in SST-1 has been successfully obtained in June 2013 where the SST-1 TF magnets have demonstrated excellent functional characteristics. The confidence boosting engineering and functional validation test results of SST-1 TF magnets as well as its performance during the recent SST-1 plasma campaign have been elaborated in this paper.
Superconducting current feeder system with associated test results for SST1 Tokamak
IEEE Transactions on Applied Superconductivity, 2004
The current feeder system (CFS) consists of 20 numbers 10 kA current leads assembled inside a specially designed cryostat, superconducting bus bars assembled in a vacuum duct with bends and the joint box interface in cryogenic environment at 4.5 K. Support structure between room temperature and 4.5 K surfaces with an intercept at 80 K has been designed specially to minimize the conduction heat load as well as to take care of the electromagnetic forces. The hydraulics design of the CFS has been optimized in order to be able to interface with the liquid helium refrigerator/liquefier. A sophisticated instrumentation and control system has been designed and developed as well as tested. The paper describe the design concepts, mechanical and hydraulic analysis, instrumentation & control system as well as some test results of the current feeder system.
Cryogenics, 2020
The Toroidal Field (TF) system of the Tore Supra/WEST tokamak comprises 18 NbTi superconducting coils, cooled by a static superfluid helium bath at 1.8 K and carrying a nominal current of 1255 A. The 19th December 2017, at the end of plasma run #52205, a quench of TFC-09 was detected first on a secondary thermohydraulical signal (helium liquid level) and triggered the current Fast Safety Discharge (FSD). A numerical model of this quench has been developed with SuperMagnet (CryoSoft). The whole TFC-09 circular coil is modelled by THEA as a single large Cable-In-Conduit Conductor (CICC) with 2028 large rectangular strands (monolithic conductors of length equal to coil average perimeter). The external quench helium relief circuit (cold and warm safety valves, rupture disk and magnetic valve with corresponding pressure set) is modelled by FLOWER. The helium pressure in the coil, upstream of the cold safety valve (maximum value of 9 bar), and the expulsed helium temperature have been used as comparison between measurements and calculations which depend on the Minimum Quench Energy (MQE) used in THEA with small initial heat deposition length (few tens of centimeters) at low field region (external leg). This energy, in the order of few kJ, is compared to the real shape and energy of neutron and gamma flux caused by highly energetic runaway electrons colliding the outboard plasma facing components and which induced the quench. The expulsed helium mass flow rate of nearly 6 kg/s during 5 s has also been calculated. This event confirms on one hand the criticality and the possible occurrence of a so called "smooth quench" caused by small initial heat deposition length and at low field region and on the other hand the important interest of secondary quench detection which can be useful for other tokamak magnets safe operation and protection.
Cryogenic Acceptance Tests of SST-1 Superconducting Coils
IEEE Transactions on Applied Superconductivity, 2015
Toroidal field (TF) and poloidal field (PF) coils of steady-state superconducting tokamak (SST-1) have been fully refurbished to ensure cryostable and low-dc-resistance interpancake and intercoil joints, helium leak tightness of the winding pack, and > 10 MΩ winding pack to ground insulation resistance under cold conditions. As per SST-1 mission mandate, all TF coils and PF3 Top had been cold tested at full operational parameters. A dedicated large coil test facility was integrated for these tests. Specially adapted solutions such as magnet preparation cum transport stand, demountable busbar supports, demountable sensor mountings, reusable joints for busbar connections inside cryostat, etc., were developed. These measures led to timely and successful completion of cold tests and integration of the magnet system on to the SST-1 machine shell. The functionality of various diagnostics of the magnet system was also established during these tests. Details of coil refurbishment, test facility, test campaigns, and some important test results are reported in this paper.
IOP Conference Series: Materials Science and Engineering, 2019
Recent experiments of SST-1 have shown that cryogenic heat loads are more than installed cold capacity. Due to this fact, the system cool down goes into the status-quo in temperatures at ~12K and further cool down is not possible. This issue can be resolved in three folds i.e. by grouping and distribution of the PF coils, optimization of the cryogenic plant process and heat loads reduction. First, we replaced common PF coils distribution to three groups having equal path lengths. Secondly, providing the best possible pressure heads to each PF groups during cool down and using turbine-C to get cold capacity with active cooling of all paths. Third is the heat loads reduction at some parts of SST-1. While adopting the same, it has been shown that the simultaneous cool down of the TF and PF coils are possible while achieving superconducting transition in all the coils except PF-5(lower).
TPX superconducting tokamak magnet system 1995 design and status overview
Proceedings of 16th International Symposium on Fusion Engineering, 1995
The TPX magnet preliminary design effort i s summarized. Key results and accomplishments during preliminary design and supporting R&D arc discussed, including conductor development, quench detection, T F and PF magnet design, conductor bending and forming, reaction heat treating, helium stubs, and winding pack insulation.
High-vacuum compatibility tests of SST-1 superconducting magnets
Journal of Physics: Conference Series, 2012
SST-1 Tokamak is under commissioning at Institute for Plasma Research in mission mode. It comprises of a toroidal doughnut shaped plasma chamber, surrounded by liquid helium cooled superconducting magnets and LN 2 thermal shields, housed inside the cryostat chamber. The superconducting magnet system of SST-1 consists of toroidal field (TF) magnets and poloidal field (PF) magnets and will be operated at internal supercritical helium pressure of 4.5 bar (a) under very low temperature of 4.5 K and carrying a DC current of 10 kA. Highvacuum compatibility up to low-pressure 1 × 10-5 mbar is one of the most essential features of these superconducting magnets in order to avoid the heat losses due to conduction and convection. This paper describes the extensive tests carried out under representative conditions to ensure the high-vacuum compatibility of the SST-1 magnets before assembly to the main system.
Design and Construction of JT-60SA Superconducting Magnet System
The upgrade of JT-60U magnet system to superconducting coils (JT-60SA) is progressing by both parties of Japanese government and European commission (EU) in the framework of the Broader Approach agreement. The magnet system for JT-60SA consists of 18 Toroidal Field (TF) coils, a Central Solenoid (CS) with four modules, six Equilibrium Field (EF) coils. The TF coil case encloses the winding pack and is the main structural component of the magnet system. The CS consists of four independent winding pack modules, which is support from the bottom of the TF coils. The six EF coils are attached to the TF coil cases through supports with flexible plates allowing radial displacements. The feeder system is connected from each coil to the helium refrigerator and the power supply. High temperature superconducting current leads are installed in the coil terminal box connecting to the cryostat. The TF coils and HTS leads are provided by EU. CS, EF coils and feeder system are prepared by Japan. Th...