摘要:

Several large‐solid‐angle devices for collecting, at a common focus, multiply charged heavy ions from nuclear reactions have been studied. These devices use axial magnetic fields (solenoids), radial electric fields (coaxial lenses), or a combination of these. Although each system has particular advantages and disadvantages, several designs appear promising for use as practical devices.

ISSN:0034-6748    

DOI:10.1063/1.1139311

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Results are presented on the production of H−ions in a large (55×31×20 cm3) magnetic multipole discharge, which is sufficiently large to act as the plasma generator for a neutral beam injector. H−ion current densities up to 57 mA/cm2have been extracted in pulses up to 3 s in length at low energies. When the discharge is operated in deuterium, a maximum D−current density of 27 mA/cm2is obtained. The scaling laws of the H−production are consistent with production by dissociative attachment to rovibrationally excited molecules and loss by mutual recombination.

ISSN:0034-6748    

DOI:10.1063/1.1139312

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The Dudnikov type Penning source has been operated successfully with low work function LaB6cathodes in a cesium‐free discharge. It is found that the extracted H−current density is comparable to that of the cesium‐mode operation and H−current density of 350 mA/cm2have been obtained for an arc current of 55 A. Discharge current as high as 100 A has also been achieved for short pulse durations. The H−yield is closely related to the source geometry and the applied magnetic field. Experimental results demonstrate that the majority of the H−ions extracted are formed by volume processes in this type of source operation.

ISSN:0034-6748    

DOI:10.1063/1.1139313

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

We describe a simple time‐resolving Thomson spectrometer system which can provide the temporal information of ions produced by a pulsed source, in addition to the time‐integrated information. The electric field in a conventional spectrometer is modulated by a time‐varying field. It is shown that from the resulting spectrogram, the time‐resolved quantities associated with the ions can be deduced. Experimental results with plasma focus produced ions are given as an example.

ISSN:0034-6748    

DOI:10.1063/1.1139314

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The pointing noise of light beams generated by light emitting diodes (LEDs) and laser diodes are investigated and compared with the stability of the He–Ne laser and the incandescent lamp beam. LEDs have superior pointing noise characteristics compared to other light sources with their angular position drift of only about 50 nrad.

ISSN:0034-6748    

DOI:10.1063/1.1139315

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

This paper describes a measuring system which automatically selects and identifies angularly deflected electromagnetic rays of a pencil beam exploring a dispersive medium. The schlieren deflection is dependent on the refractivity gradient transverse to the ray path. This yields fairly localized measurement of material inhomogeneities. Applied for the first time to a tokamak plasma, this schlieren method yields fast time and good spatial resolution measurement of the particle density distribution. Without any need for data inversion this method also delivers monitor signals of the center‐core peak density and flattening of the parabolic particle density distribution. Schlieren measurements of magnetohydrodynamic particle density perturbation give an insight into plasma transport and collapse mechanisms.

ISSN:0034-6748    

DOI:10.1063/1.1139316

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

A high‐wavelength resolution (&Dgr;&lgr;≤0.02 A˚) spectroscopic apparatus has been developed and applied to the measurements of spectral line profiles emitted by thermonuclear plasmas yielding important plasma parameters, such as ion temperature and fluid velocity. The experimental apparatus consists of a spectrometer, an optical multichannel analyzer (OMA), and a lens. It allows precise wavelength measurements (&Dgr;&lgr;error≤0.02 A˚) when a computer and a ThI electrodeless discharge lamp (EDL) are used to calibrate the instrument. The apparatus yields single‐shot space and time‐resolved spectra for radiation in the 2000–8000‐A˚ range.

ISSN:0034-6748    

DOI:10.1063/1.1139317

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

A novel TE discharge, 15‐mm aperture, multiatmosphere, CO2laser amplifier is described, with measured electrical characteristics and gain measurements on the 9.294‐&mgr;m, 9R(16) line. The electrical circuit used in this amplifier is a realistic alternative to the Marx bank or conventionalLCinversion circuit and, similarly, it would be useful for excitation of other gas lasers as well. This automatically preionized, double‐sided, fourfoldLCinversion circuit uses only one spark gap, and it is shown to provide small‐signal gains of 5.7% cm−1, at 120 J l−1 atm−1and 10 atm. The generalization to ann–stage device, which would be suitable for higher pressures, and larger apertures, is discussed.

ISSN:0034-6748    

DOI:10.1063/1.1139318

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

An easily assembled computer‐controlled tunneling spectrometer is described. Spectral acquisition time is user selectable over a wide range. Low‐resolution spectra may be taken rapidly (about 30s/scan) or very slow scans with long time exponential averaging may be chosen. Data are obtained using a two‐phase lock‐in in magnitude mode so that no phasing of the lock‐in amplifier is required. The advantages of this system are discussed and some representative data presented.

ISSN:0034-6748    

DOI:10.1063/1.1139319

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

This paper describes an improved apparatus to measure dielectric constants and dissipation factors using a resonance technique. The measurements can be made rapidly and accurately without appreciable systematic error in the wide frequency range from 1 kHz to 100 MHz. This apparatus uses the half power‐gap variation method or the half power‐varying gap‐immersion method for solid‐plate specimens and the solid‐plate displacement method for liquid specimens. The electrode system is 30 mm in diameter and has a shield ring to avoid the edge capacitance effect, guards against surface current leakage, and variable air capacitors to set the electrode gap at any arbitrary value. To detect a very small power loss, the resonance voltages in circuits withQ&bartil;100 are stabilized to −86 dB at a constant ambient temperature. We use phase detectors so that the electrode gap and the voltage at resonance can easily be read from the digital panel meter and the digital voltmeter. No corrections are necessary even at a high frequency of 100 MHz. The accuracy of measurements made using the half power‐varying gap‐immersion method is within 0.2% for the dielectric constant and 3% for the dissipation factor without marked degradation over the entire frequency range.

ISSN:0034-6748    

DOI:10.1063/1.1139320

出版商:AIP    

年代:1987

数据来源: AIP