A. Radovinsky

Test of the ITER central solenoid model coil and CS insert

The Central Solenoid Model Coil (CSMC) was designed and built from 1993 to 1999 by an ITER collaboration between the U.S. and Japan, with contributions from the European Union and the Russian Federation. The main goal of the project was to establish the superconducting magnet technology necessary for a large-scale fusion experimental reactor. Three heavily instrumented insert coils were built to cover a wide operational space for testing. The CS Insert, built by Japan, was tested in April-August of 2000. The TF Insert, built by Russian Federation, will be tested in the fall of 2001. The NbAl Insert, built by Japan, will be tested in 2002. The testing takes place in the CSMC Test Facility at the Japan Atomic Energy Research Institute, Naka, Japan. The CSMC was charged successfully without training to its design current of 46 kA to produce 13 T in the magnet bore. The stored energy at 46 kA was 640 MJ. This paper presents the main results of the CSMC and the CS Insert testing-magnet critical parameters, ac losses, joint performance, quench characteristics and some results of the post-test analysis.

ITER CS model coil and CS insert test results

The inner and outer modules of the central solenoid model coil (CSMC) were built by US and Japanese home teams in collaboration with European and Russian teams to demonstrate the feasibility of a superconducting central solenoid for ITER and other large tokamak reactors. The CSMC mass is about 120 t; OD is about 3.6 m and the stored energy is 640 MJ at 36 kA and peak field of 13 T. Testing of the CSMC and the CS insert took place at Japan Atomic Energy Research Institute (JAERI) from mid March until mid August 2000. This paper presents the main results of the tests performed,.

The Levitated Dipole Experiment (LDX) magnet system

In the Levitated Dipole Experiment (LDX), a hot plasma is formed about a levitating superconducting dipole magnet in the center of a 5 m diameter vacuum vessel. The levitated magnet is suspended magnetically during an eight hour experimental run, then lowered and recooled overnight. The floating F-coil magnet consists of a layer-wound magnet with 4 sections, designed to wrap flux lines closely about the outside of the levitated cryostat. The conductor is a niobium-tin Rutherford cable, with enough stabilizer to permit passive quench protection. Lead strips are used as thermal capacitors to slow coil heating. An optimized system of bumpers and cold-mass supports reduces heat leak into the helium vessel. Airbags catch the floating coil on quenches and faults, preventing collision with the vacuum vessel.

Design, fabrication and test of the react and wind, Nb3Sn, LDX floating coil

The Levitated Dipole Experiment (LDX) is an innovative approach to explore the magnetic confinement of fusion plasma. A superconducting solenoid (floating coil) is magnetically levitated for up to 8 hours in the center of a 5-meter diameter vacuum vessel. The floating coil maximum field is 5.3 T, and a react-and-wind Nb/sub 3/Sn conductor was selected to enable continued field production as the coil warms from 5 K during the experiment up to a final temperature of about 10 K. The coil is wound using an 18-strand Rutherford cable soldered into a half-hard copper channel, and is self protected during quench. The coil is insulated during winding and then vacuum impregnated with epoxy. The impregnated coil is tested with 2 kA operating current at 4.2 K, and then a single, low resistance joint is formed at the outer diameter of the coil before the coil is enclosed in its toroidal helium vessel. This paper presents details of the coil design and manufacturing procedures, with special attention to the techniques used to protect the coil from excessive strain damage throughout the manufacturing process.

The KSTAR superconducting magnet system

The Korean Superconducting Tokamak Advanced Research (KSTAR) at the Korea Basic Science Institute in Taejon will be the first Tokamak with an advanced all superconducting magnet system, including toroidal field (TF), poloidal field (PF),and field error correction (FEC) coils. The conductors are all cable-in-conduit (CICC) superconductors with a single conduit similar to those in the International Thermonuclear Experimental Reactor (ITER).

Charging magnet for the floating coil of LDX

The charging coil (C-coil) for the joint Columbia University/MIT Levitated Dipole Experiment (LDX) is under development jointly by MIT and the Efremov Institute. The NbTi superconducting C-coil serves to charge/discharge inductively the floating superconducting magnet to/from 2277 A when it is resting in the charging port at the bottom of the LDX vacuum vessel. The C-coil is designed for 3200 charge-discharge cycles. The solenoid magnet is installed in a low heat leak liquid helium cryostat with a warm bore of more than 1 m. The magnet protection system has an external dump resistor, which dissipates most of the 12 MJ stored during a quench.

High temperature superconducting levitation coil for the Levitated Dipole Experiment (LDX)

The Levitated Dipole Experiment (LDX) is an innovative approach to explore the magnetic confinement of fusion plasmas. A superconducting solenoid (floating coil) is magnetically levitated for up to 8 hours in the center of a 5-meter diameter vacuum vessel. This coil is supported by a levitating coil (L-Coil) on top of the vacuum vessel. In the initial machine design, this levitating coil was a water-cooled copper solenoid, and was the experiments single largest load on the available water system. The main benefit of using a high temperature superconducting coil is the ability to apply more auxiliary heating power to the plasma. However, this coil will also be the first high temperature superconducting coil to be used in a US fusion program experiment. The high temperature superconducting L-Coil is a solenoid, using a two-in-hand winding of a commercially available 0.17 mm/spl times/3.1 mm tape by American Superconductor Corporation with a critical current of 62 A at 77 K and self-field. The L-Coil will be operated at 0.9 T and 20 K. The L-Coil has a protection circuit that not only protects it against overheating in the event of quench, but also against F-Coil collision in the event of a control failure.

TPX superconducting tokamak magnet system 1995 design and status overview

The TPX magnet preliminary design effort is summarized. Key results and accomplishments during preliminary design and supporting R&D are discussed, including conductor development, quench detection, TF and PF magnet design, conductor bending and forming, reaction heat treating, helium stubs, and winding pack insulation.

Superconducting magnets for Maglifter launch assist sleds

The Maglifter is an electromagnetic catapult being considered by NASA to reduce the cost of lifting a payload into space. The system would accelerate a vehicle of up to 590 tonnes to a final velocity of 268 m/s at an acceleration of 2 g. Superconducting coils are considered for levitation because they permit track-to-vehicle clearances of more than 95 mm. The high clearances reduce tolerances and maintenance costs, and allow a system with permanently deployed wheels for take- off and emergency landing. Cable-in-conduit conductors (CICC) were selected because of their high electrical and mechanical strength, as well as high energy margin for stability. The selected coil shape is a pair of racetrack coils forming a module with four modules on a sled. The superconducting levitation modules weigh about 4% of the gross lift off weight and are capable of achieving lift off at about 20 m/s. The maximum magnetic drag power is negligible compared to the power required for acceleration.

The ITER Central Solenoid

The central solenoid for the International Thermonuclear Experimental Reactor (ITER), a fusion tokamak experiment with the goal of generating 500 MW of fusion power with high gain (Q>10), must provide most of the volt-seconds needed to induce and sustain a 15 MA plasma for burn times of >400 s. The 6.4 GJ central solenoid design requires a 45 kA conductor and has a peak field of 13 T. The central solenoid consists of six pancake-wound modules, stacked vertically, and held in axial compression by an external structure. The five-stage cable has 1/3 copper and 2/3 advanced Nb3Sn strands in a thick superalloy conduit and is cooled by the forced-flow of supercritical helium through the cable space. Key design issues include the qualification of a conduit with adequate fatigue strength, avoiding filament damage from transverse Lorentz loads, eliminating axial tension in the winding insulation, and qualification of space-saving intramodule butt joints