The Central Solenoid (CS) model coil programme was performed since 1992 as one of the projects in the Engineering Design Activity (EDA) of the International Thermonuclear Experimental Reactor (ITER). The CS model coil programme involves a plan to develop the Toroidal Filed (TF) insert to demonstrate the conductor performance of ITER TF coils under a magnetic flux density of 13T. The TF insert was fabricated by Russia and tested by Japan under the framework of the ITER-EDA. The TF insert developed a single-layer solenoid with nine turns. It is wound with a cable-in-conduit (CIC) conductor which consists of 1, 152 Nb3Sn strands, a thin titanium jacket and a central channel. The outer diameter, height and weight of the TF insert are 1.56m, 3.2m and 3.1ton, respectively. Fabrication of the TF insert was completed in May 2001 at the D. V. Efremov Scientific Research Institute for Electrophysical Apparatus (Efremov institute) in St. Petersburg, Russia. The TF insert was then transported to the Japan Atomic Energy Research Institute (JAERI). Installation of the TF insert to CS model coil test facility was completed in August, 2001. Experiments including the cooldown and warmup processes, were completed in November 2001. The TF insert was charged to 13T with 46kA without any instability under a back up magnetic field from the CS model coil. This report introduces an overview of the fabrication, installation and experiments for the TF insert conducted under collaboration between Japan and Russia.
The Central Solenoid (CS) model coil program was established in 1992 as one of projects in the Engineering Design Activities (EDA) of the International Thermonuclear Experimental Reacter (ITER). Current sharing temperature (Tcs) measurement of an ITER toroidal field insert (TF insert) was performed. The coil is a Nb3Sn superconducting coil, and was installed inside of the ITER CS model coil as a backup field coil. The relation between the voltage of an individual strand composed of the TF insert conductor and the measured voltage using the taps on the jacket were investigated, and evaluation method for Tcs measurement was established. The obtained results show that there was a discrepancy between the expected value from the strand data and the measured value, which is lower by about 1.2K. Some discrepancy was observed just after cooling down the insert before energizing.
The Central Solenoid (CS) model coil program was established in 1992 as one of projects for the Engineering Design Activities of the International Thermonuclear Experimental Reactor (ITER) and has been an ongoing activity ever since. A CS model coil and a Toroidal Field (TF) Insert have been developed and tested successfully. The TF insert is comprised of a cable-in-conduit conductor that consists of 1, 152 superconducting strands bundled on a central cooling channel. An experiment was conducted to investigate the pressure drop performance of the TF insert. There were two purposes for the investigation: one to verify pressure drop prediction using correlations proposed by various researchers, and other to investigate the behavior of the pressure drop under electromagnetic forces. The pressure drop of the TF insert decreased by approximately 12% during current-carrying operation of 46kA at 13T. After several current-carrying operations, the friction factor of the TF insert finally reached a value that was approximately 10% lower than that of original state and was not recovered even without current. It is believed that the cable cross-section inside the conductor jacket became deformed due to electromagnetic force and a new flow path in the jacket was generated.
The Central Solenoid (CS) model coil program was established in 1992 as one of the projects for the Engineering Design Activity (EDA) of the International Thermonuclear Experimental Reactor (ITER). The Toroidal Field (TF) insert was developed by Russia to demonstrate TF conductor performance and tested in the bore of the CS model coil under application of a 13-T magnetic field. The TF insert was successfully charged to 46kA at 13T. In this paper, we describe the quench characteristics and results of AC loss measurements. In order to investigate the quench characteristics of the TF conductor, quench tests were performed at 46kA, 12T and 6.5K. An inductive heater 200mm in length was utilized to create artifical quenching and the currents of the TF insert and CS model coil were kept for 9s after normal zone appearance. The normal zone length was 16m, and the maximum velocity was 2m/s. The maximum temperature was estimated as 160K with slight deviation. For AC loss measurement, the mandrel is a large error source, and it is difficult to separate coupling loss at the TF insert from measured AC loss at a faster charge. Hysteresis loss was measured utilizing the calorimetric method, and the values were almost same as the expected values from strand data.
The Central Solenoid Model Coil (CS model coil) program was established in 1992 as one of the projects for the Engineering Design Activities (EDA) of the International Thermonuclear Experimental Reactor (ITER). In the year 2001, we carried out several kinds of tests using a CS model coil and a Toroidal Field (TF) insert coil. In the experiments, we measured the acoustic emission (AE) signals emitted from these coils. This was the first attempt to measure AE from the insert coil directly, as AE sensors were not attached during the previous tests conducted in 2000. In this paper, we focus our discussion on the AE signals emitted from the TF insert coil. Two kinds of data acquisition methods for the AE signals were utilized during the series of excitations: full waveform recording and AE envelope recording. Observation of the AE signals showed that the disturbances in the TF insert coil decreased with the iteration number of excitation as judged from the instantaneous AE energies and AE event count. Furthermore, we confirmed that the AE had constant distributions during a 1, 000-time-cyclic test under a back-ground-field of 13T using the CS model coil. Therefore, we obtained an important experimental result in that the TF insert coil was highly stable throughout the series of experiments.
The measurement of liquid volume under micro-gravity conditions is an important aspect of space technology. Cryogenic propellants including liquid hydrogen, liquid oxygen, and liquid natural gas will soon be handled in orbit for space transportation systems. In the present study, Helmholtz resonance is applied to measure a liquid volume. To confirm the applicability of this measurement technique to cryogens, a micro-gravity experiment using liquid nitrogen was carried out. And a theoretical model of a closed system is proposed for the practical application in orbit. A preliminary experiment with water as the test liquid was also carried out to confirm the validity of the model. We successfully detected the Helmholtz resonance frequency and its higher order harmonics. It is confirmed that the measurement method is an effective means for practical application.
The fundamental characteristics of the two-dimensional cavitating flow of liquid helium through a venturi channel near the lambda point are numerically investigated to realize the further development and high performance of new multiphase superfluid cooling systems. First, the governing equations of the cavitating flow of liquid helium based on the unsteady thermal nonequilibrium multifluid model with generalized curvilinear coordinates system are presented, and several flow characteristics are numerically calculated, taking into account the effect of superfluidity. Based on the numerical results, the two-dimensional structure of the cavitating flow of liquid helium though venturi channel is shown in detail, and it is also found that the generation of superfluid counterflow against normal fluid flow based on the thermomechanical effect is conspicuous in the large gas phase volume fraction region where the liquid-to-gas phase change actively occurs. Furthermore, it is clarified that the mechanism of the He I to He II phase transition caused by the temperature decrease is due to the deprivation of latent heat for vaporization from the liquid phase.