[en] A new method for fatigue-life assessment of a component containing defects is presented such that a probabilistic approach is incorporated into the CEGB two-criteria method. The present method assumes that aspect ratio of initial defect, proportional coefficient of fatigue crack growth law and threshold stress intensity range are treated as random variables. Examples are given to illustrate application of the method to the reliability analysis of conduit for an internally cooled cabled superconductor (ICCS) subjected to cyclic quench pressure. The possible failure mode and mechanical properties contributing to the fatigue life of the thin conduit are discussed using analytical and experimental results. 9 refs., 9 figs

[en] A water cooling passage leak which developed in a TFTR toroidal field (TF) coil has precipitated interest in developing alternative cooling options for this coil system. A test on a spare coil was performed to establish a low power heating schedule and to determine the efficacy of gas cooling the TF coils. A computer analysis was also performed using the test results to benchmark the code. The investigation of gas cooling was initiated as a contingency in the event of future irreparable leaks developing in the TF coil cooling passages. It is generally acknowledged that gas leakage into the electrical insulation would have a relatively benign effect on its dielectric strength whereas recent experience on TFTR indicates a substantial degradation of dielectric strength when wetted with water (the use of high dielectric silicone oil as an alternative coolant, is discussed elsewhere in these proceedings). The purpose of the low power heating test was to establish the proper current settings and IR drop to maintain the TF coil at a prescribed temperature of 80 degree C, in preparation for an elevated temperature dry-out cycle on the leaking coil in TFTR. 3 figs., 9 tabs

[en] Published in summary form only

[en] Published in summary form only

[en] The present situation of the design and construction of R and D superconducting conductors for Large Helical Device is reported. At first, the required properties for the conductor of LHD and the design criteria of the conductors are mentioned. Then the designed patterns of the cross sections of R and D conductors are shown. The test and estimation items of conductors are listed. Lastly, the R and D schedule are shown. (author)

[en] The magnetic fluctuations in TEXT (R = 1m, a = 0.26m, ohmically heated tokamak with a full poloidal limiter) have been extensively measured with magnetic probes in the shadow of the limiter with an instrumental range of f < 500kHz and k < 3cm^-1 (m < 80). Both radial and poloidal components are observed. Besides the low frequency, discrete low-m modes, a high frequency, featureless spectrum extends to nearly 500 kHz, but little energy is present above 250 kHz. The B^rms_p (f > 50kHz) at the limiter radius is found to be of order 10^-5T, which is too small to produce significant transport directly. Over the range of discharge parameters in TEXT, the B^rms_p (f > 50kHz) is observed to have a strong q_a dependence (q_a^-2.2) and also a density dependence (n_eo^-0.8). Furthermore, the magnetic fluctuations show a significant correlation with edge electrostatic density fluctuations measured by Langmiur probe inside the limiter radius, and extending along magnetic field lines. Phase variation of the correlated components suggests k double-prime/k perpendicular ∼ 0.005. The B_p^rms(f >50kHz) is also found to be little dependent on parallel electric field E double-prime. Magnetic fluctuations in both low and high frequency ranges have been characterized by their response to gas puffing, pellet injection, impurity injection, and the effect of an ergodic magnetic limiter. The behavior of magnetic fluctuations with electron cyclotron resonance heating (ECRH) has been also investigated in detail

[en] A simple method is proposed to suppress the breaking of magnetic surfaces which occurs in l = 2 heliotron/torsatron equilibria. With this method, fairly high beta equilibria with clearly nested magnetic surfaces can be realized without changing other physical properties such as the rotational transform profile and the well depth. (author). Letter-to-the-editor. 7 refs, 3 figs, 1 tab

[en] In CTCC-2 experiment, the initial plasma is produced by a magnetized gun and ejected into a metallic aluminum flux conserver (FC) with thickness of 15 mm. The spheromak is formed in the FC during a life time of 1.5 ms, in which the plasma is isolated from any external feeder. A choking-field-generating coil is equipped on the entrance of the spheroidal FC. The choking field is suppressing some leakage of spheromak field along the entrance duct, which is made of thin stainless steel plate (0.8 mm) for rapid penetration of the choking magnetic field. This resistive part acts as an effective plasma current limiter, which produces stable currentless region (flux hole). The flux hole increases magnetic shear without inserting a central conducting pole along the symmetric axis and is controlled to decrease with the choking field strength. Thus, in CTCC-2 spheromak, a stable oblate spheroidal boundary is rigidly fixed by the metal wall of FC and the entrance hole of FC is effectively closed by choking magnetic field, so that it is suitable to investigate precisely a fine structure of configuration. In spheromak configuration whose aspect ratio is near one, the ratio of the magnetic strength at the inner part to that at the outer part on equi-flux surface (mirror ratio) becomes very large in comparison with that of a large aspect ratio. This extreme configuration with a high mirror ratio may be associated with an anisotropic pressure effect even in collisional state like as our experimental condition. They have investigated the pressure effect on spheromak configuration in more detail. The obtained equilibrium profile is grossly explained by a theoretical profile on assuming low beta limit until now. However, the authors observe a systematic discrepancy between a measured poloidal profile and a theoretical one as mentioned

[en] Using a multilayer model of an infinitely long cylindrical plasma, the penetration of a transverse rotating magnetic field (RMF) into plasma has been investigated. The simulation shows that the transverse magnetic field can penetrate into plasma under certain conditions. The penetration is found to strongly depend on a quantity, R₃, which is the square of the ratio of the cross-sectional area of the plasma column to the skin depth. The critical condition for the RMF to penetrate into the plasma is obtained. The time evolution of axial magnetic field B_z distributions is simulated, and the B_z distribution in steady state is found to coincide with that of the experimental result. (author)

[en] The field reversed configuration (FRC) plasma had been thought to have poloidal field only, but in this experiment, toroidal field was observed. We report magnetic probe measurements on our FIX machine, and the existence of toroidal field in the FRC plasma during its translation. The magnitude of the toroidal field is 100 ∼ 150 G at the peak, and the direction of the toroidal field is counterclockwise looking toward the θ-pinch region, irrespective of the direction of the external axial field. The obtained toroidal field has a direction opposite to the toroidal field in FRX-C/LSM. (author)