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A three-frame Mach-Zehnder interferometer (TFMZI) was used for taking 3 pictures (5 ns exposure and 13 ns interpicture delay) of the imploding plasma in one z-pinch shot, which provides us a series of interferograms showing the evolution of electron density profile during z-pinch implosion stage. From these interferograms, the electron density profile ne(r , z), the velocities of plasma implosion were derived, and the plasma instabilities appearing as bubbles or fringe shearing were observed clearly. In order to study the correlation between the total energy of x-ray emission and the plasma implosion, thermopiles were also used in the experiments with TFMZI. The results of x-ray radiation diagnostics show us that a near uniform and symmetric imploding plasma shell would emit more x-ray yield than an asymmetric one, which is in good agreement with the implosion dynamics analyses.

A three-frame Mach–Zehnder interferometer (TFMZI) was developed for taking three pictures of the imploding plasma produced by one shot of fast pulsed discharge. TFMZI consists of a YAG laser, a beam splitter, and a Mach–Zehnder interferometer. By passing through the beam splitter the laser beam was split into three beams with an interbeam delay of 13 ns and each laser beam will give a snapshot of the implosion state. The measurements with the TFMZI were conducted on a small gas-puff z-pinch device and gave good results. In principle an upgraded four or (more) frame Mach–Zehnder interferometer could be constructed if much improvement was made on the TFMZI.

The cavity structure of the anode and the cathode of a pseudospark switch is an important factor for its performances. When the cathode has a cavity structure, the electric erosion on the cathode and anode is small and a concentric ring-shaped erosion pattern is observed at the central area around the apertures of both electrodes. Without the cathode cavity, the erosion becomes stronger, and the patterns become irregular and unstable. Several kinds of electrode structure have been designed and investigated. Among them, a unique cavity structure of intermediate floating electrode in pseudospark switch has a good performance. This configuration could reduce the erosion on the electrodes and increase the selfbreakdown voltage of the pseudospark switches up to 80 kV. In this paper, we have studied the influence of the electrode structure on the erosion of the electrode and the selfbreakdown characteristic of the switches.

A supersonic nozzle for a 1.5-MA gas puff Z pinch was designed and the gas flow injected out from the nozzle was measured. A miniature ionization gauge was developed to measure the density profile of the gas shell and two pressure transducers were used for determining the Mach number of the gas flow. It was found that the gas flow is not distributed symmetrically about r/sub 0/, the mean radius of the exit aperture, and the radial location for the peak of the density profile moves inwards as time goes on. When the plenum pressure is 5 atm, the maximum line mass density measured was 43 /spl mu/g/cm and the Mach number of the gas flow deduced from experiments is 4.3, which is close to the expectation: line mass density of about 50 /spl mu/g/cm and a Mach number higher than 4. The measurements indicate that if a plenum opens into a large dead volume via a finite opening valve in a gas-puff system it will not produce a steady-state solution. Then, any agreement between the measurements and the calculations based on the steady state should not be expected.

A fiber-optic current sensor (FOGS) based on a differentiating Sagnac interferometer (DSI) is demonstrated to measure high-voltage ac current in electric power systems from 5 A to 3200 A. A transducer consisting of Rogowski coil and piezoelectric cylinder (PZT) is used as the phase modulator, which is placed in the high-voltage side. The DSI is placed in the ground side. A simple analytical expression for the sensor has been derived, and the input-output performance and the temperature dependence of FOGS have been experimentally investigated. The simple sensor geometry gives high accuracy and sensitivity, wide dynamic range, and immunity from slow-variance temperature and other environmental fluctuations.

A simple knife-edge design was described that enabled easy optimization and investigation of the initial phase for the plasma focus devices. It enhanced the initial breakdown process along the insulator surface by allowing free adjustment or fine-tuning of the insulator length and by forming a sharp knife-edge with effective field emission. The plasma pinching was much improved with neutron yield equal or above that predicted by the scaling law. This knife-edge design is especially suitable for the optimization of medium and large-scale plasma focus devices where it would be otherwise rather difficult to modify the insulator configuration directly.

Experiments were carried out on a small gas-puff Z-pinch plasma device with a capacitor bank of 16 /spl mu/F and a charging voltage of 22 kV. A compact Thomson ion energy analyzer was installed on the device for determining the energy spectra of ion beam emitted from the Z-pinch plasma. The energy spectra of Argon ion beams with single, double, and triple charges were determined with the analyzer. A Mach-Zehnder laser interferometer was installed to measure the electron density and the movement of the Z-pinch plasma. The electron density of the plasma just before the pinch is larger than 9.00/spl times/10/sup 18/ cm/sup 3/, the corresponding radius and the pinch velocity of the plasma are 1.42 mm and 1.86 cm//spl mu/s, respectively.

For measuring current in three-phase plate-form busbars, this paper proposed an indirect method that used planar Rogowski coil as the current sensing part. Based on the electromagnetic induction law, Biot-Savart law and the numerical integration arithmetic, the vector potential of the busbar was calculated and the electromotive force of the planar coil for the single phase and three-phase busbar current was deduced. The relative error that was caused by vertical displacement, flat displacement and rotated displacement of coil is measured and calculated when the coil is used for the measurement of plate-form busbar current. The results of the theoretical calculation about the coil have good accordance with the experiments. More than two years of field testing shows that the current transducers based on the planar Rogowski coil proposed by this paper meets the practicality.

The development of an optical instrument transducer to measure rotor's voltage and current in power generator is described in the paper. The system is based on A/D conversion and optical fiber transmission principle. The voltage/current signal from SCR bridge of an power generator is conditioned to ADC and than the digital signal from ADC is transmitted to local module through optical fiber. The uncertainty of the OIT is estimated to be less than 0.2% in ratio and the delay time of the step response is less than 7 ms.

The designs and tests of a hybrid-optical direct current transformer (HOCT) are demonstrated, which consists of a shunt, a coil, an opto-electric transmission system and some electronics. The experiment results show that the DC measurement meets the 0.2 accuracy class standards and the harmonic measurement confirms with GB/T 14549-93 for harmonic of public power. (4 pages)

This paper introduces the principle and testing of a 220 kV active electronic current transformer (ECT) for metering and protection in power system. The field trial results of more than two years demonstrate that the ECT meets IEC6044-8 0.5 class with safety and reliability. (5 pages)

In this paper, an approach for online monitor system of vacuum circuit breaker's electrical endurance is introduced. The hidden trouble can be found and obviated in time via this monitoring system. Basal principle and arithmetic of electrical endurance of vacuum circuit breakers are introduced firstly, and then the elements and design of current sensor, signal processor, communicate unit and man-machine interface software are described respectively, finally, the running result laid out proves the success of developments of this system. (5 pages)

A fiber optic semiconductor absorption sensor for temperature measurement is presented. The sensor is based on the temperature dependence of band gas edge absorption of infrared light in semiconductor, and made of multimode optical fiber in light reflected from a GaAs semiconductor platelet configuration. The configuration reported here is small, easy to handle, and a fast response time. A light emitting diode are used as sources of analytical and reference radiations, which eliminates the influence of intensity fluctuation of the light source and that of the coupling and connecting loss of optical fibers. The sensor features the accuracy of 1/spl deg/C over a temperature range from -20/spl deg/C to 110/spl deg/C, and response time of 0.23 s//spl deg/C. The sensor is particularly suitable for temperature measurement in electrical power systems.

Summary form only given. A 1.8 kJ compact plasma focus (CPF) source operated in neon is demonstrated as a soft X-ray (SXR) source for microlithography in the wavelength range of 0.8-1.4 nm. The CPF is a four-module system. Each module uses a rail gap switching 12 capacitors each with a capacity of 0.6 /spl mu/F. It operates with peak current of 400 kA at 11.5 kV into water cooled electrodes at repetition rates up to 16 Hz to produce 300 W SXR in burst duration of several minutes. Lithographs are obtained by exposing the resist to the X-ray point source with a mask in contact with the resist. The total energy emitted is measured using PIN diodes and photoconducting diamond detectors (PCD) to be 20 J per shot with a spectrum peaked at 1 keV corresponding to the K shell lines from the neon working gas. The maximum repetition rate of 16 Hz allows lithographs to be obtained in less than 20 seconds when a reasonably sensitive resist is used.

Electronic transformers instead of electro-magnetic transformers are the developing trend. But it is still difficult for electronic transformers to put into practice because the influence of temperature and the stability of long-term operation. In this paper, an electronic combined transformer is presented. In order to obtain the steady long-term operation results, the mature sensor design technology is adopted. And then the circuit part of measuring system is designed and realized. The measuring results made in Lab show that the error of circuit part in measuring system is lower than that of 0.5 class transformer. The on-site measurement is processed at last. These testing results and corresponding analysis will be helpful for the improvement of the whole testing system.

An experiment was carried out on a small gas-puff Z-pinch plasma device with capacitor bank of 16 /spl mu/F and charging voltage 22 kV. Discharge current was measured by Rogowski coil. A compact Thomson ion energy analyzer was installed in the discharge chamber for determining the energy spectra of ion beam emitted from the Z-pinch plasma. The energy spectra of argon ion beams with single, double and triple charges were determined using the analyzer. A Mach-Zehnder laser interferometer was installed to measure the electron density and the movement of Z-pinch plasma. The electron density of the plasma just before pinch instant is larger than 9.00/spl times/10/sup 18//cm/sup 3/, the corresponding radius and the pinch velocity of the plasma are 1.42 mm and 1.86 cm//spl mu/s, respectively. The yield and the time variation of X-ray emitted from the pinch plasma were also measured.

A compact repetitive Marx generator has been designed, built and tested. The generator of 8 stages is an L-C ring that consists of 8 capacitors (0.039 uF per capacitor) and 16 isolating inductors (128 uH per inductor). The generator was quickly charged to 25 kV within a charging time less than 52 microseconds by a DC charging source via a charging spark gap and a matching resistor of 81 Ohm that is equal to the characteristic impedance of the LC ring. A noise-immune two-channel trigger system was constructed for repetitively triggering one charging spark gap and the first two discharging spark gaps (there are 9 discharging spark gaps in the generator) in order of experiment. Due to the limited capacity of the DC charging source the generator was tested at a low repetition rate of 5 Hz with an output voltage about 170 kV (efficiency 85%).

Summary form only given. A small gas-puff Z-pinch plasma device is composed of a capacitor energy storage bank (capacitance=16.3 /spl mu/F, charging voltage=23 kV), field distortion switches, a discharge chamber, vacuum pumping system, fast operation gas valve and diagnostics. The amplitude and the period of discharge current are 230 kA and 9.6 /spl mu/s, respectively. Firstly, a hollow gas shell is produced by injecting gas through an annular nozzle from the fast operation valve. Then initiating the switches, a high pulsed current flows through the gas shell to produce a plasma and form hot pinch spots, from which intense X-rays and ion beams are emitted. A compact Thomson ion energy analyzer is installed inside the gas-puff Z-pinch device. By using the analyzer, up to five clear parabolas produced by argon ion bombardment on CR-39 plastic target have been observed. The parabolas are formed by Ar/sup +/, Ar/sup 2+/, Ar/sup 3+/, Ar/sup 4+/ and Ar/sup 5+/ ions. In our experiments, the range of the energy of Ar/sup +/, Ar/sup 2+/ and Ar/sup 3+/ ions are below 400 keV, 700 keV and 1 MeV, respectively.

Summary form only given, as follows. The gas puff nozzles for two neon gas-puff z-pinches were designed and tested. The first z-pinch is driven by a high current fast pulsed-power generator (1.5 MA, 80 ns) and the second one by a low current slow generator (240 kA, 2 /spl mu/s). In order to maximize the X-radiation from the z-pinch the initial radius and line mass density of the gas shell was optimized for the particular pulsed-power generator. A miniature ionization gauge was designed and constructed. With this specially designed gauge the density profiles of the puffed gas shells were measured. The density profiles were also obtained by numerical simulation. The experimental and calculated density profiles were compared and the line mass density was deduced. It was found that the calculated implosion time from 0D-model (slug-model) with the deduced line mass density agrees well with that observed in the experiment. Two fast responding pressure probes were used in the experiments on the supersonic gas shell. One probe is installed at a position just before the throat of the nozzle and another at the exit of the nozzle. The two probes method yields local Mach number of 4 for the puffed gas shell.

In order to develop a high hold-off voltage (over 60 kV) pseudospark switch (PSS), the parameters which affect the hold-off voltage such as the working gas, the pressure, the gap distance and the hole diameter of the electrodes etc. have been studied. The experiment results show that helium is a best choice as the working gas; the hold-off voltage inverses with two gap distance of the electrodes and the diameter of the hole on the electrodes. A new type of two stage PSS which possesses a hollow intermediate electrode has been developed. The self-breakdown curve of the improved two-stage PSS is shifted to higher pressures corresponding to that of the one-stage PSS and the ordinary two-stage PSS which possesses a plane intermediate electrode. Then it can operate at higher voltages. With the same condition, the erosion caused by discharge on the electrodes can be lowered and the lifetime is prolonged.

Summary form only given, as follows. A pseudospark discharge is a specific type of gas discharge, which operates at low pressure with axially symmetric parallel electrodes and central holes on the electrodes. The discharge is characterized by a very rapid breakdown phase, during which high-density particle beams can be extracted and rapid increasing rate of current can be achieved. Based on these, the pseudospark has become of interest in closing switches, in producing well-pinched high intensity electron or ion beams. The cavity structure of cathode in pseudospark device is important factor to determine the performance of the device. With and without a cavity behind the cathode aperture, the erosion pattern of the pseudospark discharge was experimentally investigated. With the hollow cathode cavity, a very small and stable erosion pattern by electron-beam generated from the spark was formed on the opposite surface inside the anode cavity and stable concentric ring-shaped erosion patterns were observed at the central area around the apertures on the electrodes. Without the hollow cathode cavity, the patterns became irregular and unstable. These results revealed that the hollow cathode cavity plays an essential role to the stability of pseudospark discharge in the pseudospark and to the generation of a well-pinched electron-beam. The cavity structure of intermediate floating electrode can also improve the self-breakdown performance of pseudospark switch. We have compared the hold-off voltage of two kinds of pseudospark switches: one with plane intermediate electrode, another with an intermediate cavity electrode. The experimental result revealed the later one has higher self-breakdown voltage (over 80 kV) and can be operated at higher gas pressure. Relevant figures, pictures and data will be presented.

Summary form only given, as follows. This paper describes a pulsed X-ray source that has been developed and investigated. Hydrogen is injected into the DPF-250 device with pressure (4/spl sim/6) Torr in the discharge chamber. The X-ray photo energy spectrum was measured by LIF thermoluminescence dose elements (TLDS) matched different filters of several materials. Six filters were selected and their thick are: beryllium-100, 500, aluminum-27.4, copper-10, 49, 20.33 and 200 /spl mu/m. Therefore, the X-ray energy spectra we have measured are about (3/spl sim/60) keV and totalling 70% of the total spectral emission at hu

Summary form only given. Experimental studies on X-ray emission and energy spectra of the ion beam have been conducted on a small gas-puff Z-pinch plasma device (ZP). The ZP consists of a capacitor bank and a discharge chamber, which includes a fast gas valve, an ultrasonic nozzle, and a pair of electrodes. The effects on the X-ray yield of nozzle configuration, gas filling pressure, the charged voltage of the capacitor bank, and pinch current have been investigated. In addition to the powerful soft-X-ray pulse, a powerful ion beam is simultaneously produced. Such an ion beam usually reduces the quality of the X-rays for application. In order to improve the quality of the X-rays a compact Thomson analyzer was used to study the energy spectra, ion species, and charge state of the ion beam.

Summary form only given. A three-dimensional and totally self-consistent analytical model for glow discharge plasma has been developed. All the analytic expressions attained from the model completely satisfy the real boundary conditions and the governing equations, which consist of the continuity equations and transport equations of charged particles, Poisson's equation, and the Maxwell equation. Using the mode index scheme, the model can be readily employed in a wide range of application. A systematic series of experiments has been carried out to verify the theoretical predictions, and good agreement was obtained.

The self-breakdown characteristics (SBC) of pseudospark switches (PSS) with different structure have been experimentally investigated. Two kinds of double-stage PSS with unique structure have been developed. One possesses intermediate cavity electrode and there are two co-axial holes on the upper and lower walls. The another one possesses a plane intermediate electrode with three holes arranged in an equilateral triangle about the center. The SBC of the two kinds of two-gap PSS are shifted to higher-pressure range compared with the single-gap PSS and the ordinary two-gap PSS. They are suitable for developing high hold-off voltage PSS.