No abstract available

No abstract available

[en] In the superconducting tokamak device JT-60SA, a power supply system that supplies and controls the DC power for the superconducting toroidal and poloidal magnetic field coils is indispensable for use in plasma control. This system is a large-scale power supply system that effectively reuses the existing power supply system for the critical plasma test device JT-60 and combines it with a newly fabricated power source. This paper introduces the overall configuration and features of the large power supply system that supplies power to the superconducting coils, and various power supply devices that constitute the system. (A.O.)

No abstract available

[en] Metal vapor vacuum arc ion sources have several unique characteristics. They are easy to operate and produce high ion flux. Arc sources do not require toxic compounds and they can generate a variety of single and mixed ion species that are difficult to obtain with gas sources. Arc sources are particularly attractive for producing boron ions, a critical species for ion implantation. This paper describes progress on a Phase 2 SBIR program to improve vacuum arc source technology. In the area of diagnostics, the authors have tested a versatile time-of-flight detector to analyze the ion content of flowing plasmas. The compact unit and modular power supply has application to source analysis and plasma processing experiments. Two promising arc triggering methods for long-term operation have been demonstrated. The first uses a piezo-electric pulse valve to inject a short pulse of starting gas directly in the arc gap. The second uses a staged vacuum arc to create an instantaneous high density of cathode material. This inexpensive and effective trigger is a modular unit that can easily be incorporated in a variety of discharge system. Source development has centered on long-pulse units (10--50 ms) with applied local magnetic fields to improve extraction efficiency and arc stability. Experiments with several configurations have led to a compact unit that mounts on a standard 2.75 inch Conflat flange. The source is simple to disassemble for cathode replacement. Triggering is easy because the source uses a ground cathode configuration. Arrays of these sources can be run in parallel to provide high ion fluxes for processing applications. The most significant recent development is the demonstration of boron ion generation using lanthanum hexaboride cathodes. In initial experiments, the source produced boron fluxes of approximately 5 mA/cm² over a 150 ms pulse. Stable operation was observed at arc currents as low as 5 A

[en] In a structural system with piezoelectric actuators, a damping effect can be achieved by properly switching the voltage on the actuators. Switched voltage methods based on piezoelectric actuators, including active bang–bang control and semi-active synchronized switch damping methods, have become an important category of vibration damping approach. Since the switching phase and switching frequency are critical factors to damping performance, their influence on converted energy in a piezoelectric actuator is investigated under the condition that the switched voltage is constant. The converted energy with randomly switched voltage is also investigated theoretically and numerically. Finally an example of beam vibration with synchronized switch damping on inductor (SSDI) control and synchronized switch damping on voltage source (SSDV) control is used to illustrate how the switching frequency can affect the control performance of different modes in a multiple-degree-of-freedom system

[en] AC-DC converters employed for harvesting power from piezoelectric transducers can be divided into linear (i.e. diode bridge) and non-linear (i.e. synchronized switch harvesting on inductor, SSHI). This paper presents an analytical technique based on the measurement of the impedance circle of the piezoelectric element to determine whether either diode bridge or SSHI converter harvests more of the available power at the piezoelectric element

[en] The high-field magnet consists of several single concentrical coils of different thickness and length, being mechanically and electrically separated from each other along their winding length. They are contained in a casing and have got distances with respect to each other, coolant being able to flow through the interspaces. The windings of each single coil are glued to each other by means of adhesive or casting resin, which may be mixed with silanized glass spheres. (RW)

[en] Piezoelectric shunt damping with mechanical structures has been an active research topic for several years. Standard passive techniques suffer from a very limited and frequency-dependent damping performance. Recently, semi-active switching techniques—namely SSDI (synchronized switch damping on inductor) and SSDV (synchronized switch damping on voltage source) techniques—have been proposed, which are capable of adapting to variations of the excitation frequency without reduction in performance. Crucial for the damping performance is the tuning of the shunt parameters and the precise switching sequence. In this paper, an analytical analysis of the switching technique is presented, which includes the influence of all shunt parameters and the switching times. New results concerning the optimal tuning of the inductance and the switching sequence are obtained, and it is shown that the enhanced SSDV technique can be equated with the SSDI technique, albeit with an increased effective piezoelectric force factor. Measurements are conducted to validate the theoretical results

[en] A superconducting microbridge has been used as a probe to detect quasiparticle diffusion currents and ''heating'', produced by a phase-slip center (PSC) in a second microbridge. The critical current of the detector is modulated by the voltage V/sub PSC/ across the PSC. This modulation provides a measure of quasiparticle current I/sub Q/ thru the PSC and gives I/sub Q/ = V/sub PSC//R/sub D/ for low voltages, R/sub D/ being the high-current differential resistance of the PSC