摘要:

A prototype switching system has been developed which can switch 20 kA at 230 V furnished by low‐voltage dc generators at the National Magnet Laboratory. The energy is used to generate quasistatic magnetic fields in liquid‐nitrogen‐cooled copper coils for times approaching 1 s. The present arrangement is limited to fields up to 40 T. The silicon‐controlled rectifier switching system, protective devices, circuit operation, and magnet structures are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1135684

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

An integrated system, cryostat, electronics, and computer used for detailed resistivity measurements during low‐temperature irradiations and anneals of metals is described. The thermal response time and rate of heat removal from the specimens are optimized. The system has excellent stability for extended isothermal anneals; measurements of deviations from Mathiessen’s rule are discussed to illustrate this feature. Examples are given of the use of the system to determine dense sets of thermal activation energies during anneals through state I. These determinations are made by linear heating at different rates during recombinations of close Frenkel pairs, and by abruptly and repeatedly changing the annealing temperature during the recovery of more widely separated pairs.

ISSN:0034-6748    

DOI:10.1063/1.1135685

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

A repetitive, tunable, high‐power vacuum ultraviolet laser operating on the 172‐nm bound–free transition in xenon has been developed for use in photochemistry, selective excitation spectroscopy, and in the generation of coherent radiation in the XUV spectral region. A compact high‐voltage generator is employed in conjunction with a coaxial cold‐cathode diode to pump high‐pressure xenon at a repetition rate of up to 10 Hz, though at present gas heating limits the operation of the laser to 0.5 Hz. The apparatus has been designed for compatibility with fluorine, and is consequently a suitable pumping source for the rare gas halide exciplex lasers. The gas handling techniques which enabled reliable, reproducible laser action to be achieved in xenon for several hundred pulses are described.

ISSN:0034-6748    

DOI:10.1063/1.1135686

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

A high‐speed digital image processor combined with a flying spot scanner and special purpose hardware for two‐dimensional convolution has been developed. This processor is applicable to image enhancement, image restoration, and feature extraction. The parallel and/or serial architectures of the processor enable digital image processing for a high‐resolution image at a fast process rate. Realization of the high‐speed operation of two‐dimensional convolution is greatly due to the special scanning method of a flying spot scanner. This processor is well suited to process the image recorded on the photographic film by means of the two‐dimensional digital filtering technique. Some experimental results are given to verify the capability of the developed processor.

ISSN:0034-6748    

DOI:10.1063/1.1135687

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The design and performance of a 2.25‐cm2‐aperture Pockels cell system for 10‐&mgr;m radiation is described. Pulses as short as 90 ps can be reliably generated with this device.

ISSN:0034-6748    

DOI:10.1063/1.1135688

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

A semiautomatic setup is described which provides the destruction‐free measurement of breakdown voltages of thin‐film structures for applications like process control and quality prediction. The method of measuring the breakdown voltage consists in feeding a constant current to the thin‐film device and analyzing the voltage buildup across the device. This method has been described in a recent paper. The setup provides the successive analysis of breakdown behavior of a given matrix of wafer dots by means of a positioning table, an electropneumatic prober, and a microprocessor‐controlled measurement unit via handshake commands. The results are given in a histogram form.

ISSN:0034-6748    

DOI:10.1063/1.1135689

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

A fast (∼300 ns), large‐signal (≳1 V), free‐standing foil bolometer was developed for measuring ultrasoft x‐ray burst fluences. The results of bolometer measurements of the radiation output of an imploding foil liner plasma indicate yields of several tens of kJ, assuming isotropic emission. This is in substantial agreement with filtered metal photocathode (x‐ray diode) measurements. The bolometer design, response function, and comparison with x‐ray photodiode data are discussed. This type of bolometer is particularly applicable to radiation measurements of high‐energy, destructive pulsed plasmas such as high‐energy imploding liner plasmas.

ISSN:0034-6748    

DOI:10.1063/1.1135690

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

A multichannel neutral‐analyzer system developed for the analysis of charge‐exchange flux from magnetically confined plasma is described. The system uses tandem magnetic–electrostatic deflection of ions produced from neutrals stripped in a gas cell to obtain the energy spectra of specific charge‐to‐mass‐ratio species. The analyzer is collimated with a spatial resolution of 2 cm FWHM at the plasma and is movable so that radial scans of charge‐exchange flux can be made. Data are recorded digitally, allowing frequency response of fluctuations in charge‐exchange flux up to 50 kHz. The calibration procedure employs an auxiliary single‐channel analyzer calibrated over the full energy range of the multichannel instrument with an atomic‐beam setup. Typical data obtained from the 2XIIB neutral‐beam‐injected mirror machine are briefly presented.

ISSN:0034-6748    

DOI:10.1063/1.1135679

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

A four‐framing Mach–Zehnder interferometer system which has variable intervals from frame to frame is developed. TEA N2lasers that are operated with atmospheric‐pressure N2gas are employed as light sources. Applicability of the system is demonstrated for a rapidly changing plasma in the plasma focus discharge.

ISSN:0034-6748    

DOI:10.1063/1.1135680

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

A method is described for measuring ultrasonic velocity and attenuation simultaneously by sampling echo pulses along with the repetition rate of velocity measurements. This is achieved by extending the pulse superposition method. This system enables us to measure the attenuation coefficient with a precision of 0.001 dB/cm, and the ultrasonic velocity with better precision than 1 part in 106. Velocity measurements can be made automatically up to five times the initial round trip time and can also track fast changes of 50 ms. Since the operation under thep=1 condition can be applied, the system can be used for the measurements of high‐loss materials.

ISSN:0034-6748    

DOI:10.1063/1.1135681

出版商:AIP    

年代:1979

数据来源: AIP