摘要:

The results of an investigation on the extraction of volume‐produced H−ions from several plasma sources, characterized by different magnetic multicusp configurations, as well as from a plasma source with no magnetic containment field, are presented. In all these configurations the extracted negative ion current can be increased and the electron current reduced by a suitable choice of the plasma electrode area and positive bias and of the extraction aperture area. This indicates that the variation of the extracted negative ion current due to the plasma electrode bias is an electrostatic effect. A significant effect of the plasma electrode bias upon the electron density and temperature is only observed in the neighborhood of the plasma electrode, while in the plasma center the negative ion and electron density are unaffected.

ISSN:0034-6748    

DOI:10.1063/1.1138197

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

A directly heated lanthanum hexaboride tapered filament has been tested in a plasma generator. A uniform temperature distribution at 1820 K has been achieved. The heating and cooling power calculated from measured quantities are balanced. A maximum arc current of 80 A was obtained, limited only by the power supply and plasma generator. The corresponding hydrogen ion current density was 0.6 A/cm2when the arc voltage was 80 V and the filament heater current was about 5 A. The filament was capable of emitting 100 A of current at an operating temperature of 1900 K. The estimated lifetime for this filament is 900 h.

ISSN:0034-6748    

DOI:10.1063/1.1138198

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Two‐dimensional spatially resolvedKshell spectra from hot (Te&bartil;40–400 eV), dense (ne&bartil;1019–1021cm−3) aluminum plasmas have been recorded using a convex curved KAP crystal spectrograph in a dispersion mapping mode with an orthogonal imaging slit. The approximately 1‐cm‐diameter, 2‐cm‐long cylindrical source was viewed on end, yielding axially and temporally integrated spectra. The relative intensities of the lines and recombination continua were used to estimate local temperatures and densities. The measurement technique is reviewed and representative analysis and results are presented in this paper.

ISSN:0034-6748    

DOI:10.1063/1.1138199

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

A new method for measuring the electron density spatial profile has been successfully tested on the tokamak of Fontenay aux Roses (TFR). This method is based on the total reflection experienced by a wave of frequencyFon the layer whereF=Fpe(r). The experimental results show that the maximum electron density in the discharge is also easily measured and that accurate determination of a density profile can be obtained with a time resolution of 5 ms. This diagnostic is well adapted to all fusion devices where access to the total plasma cross section is limited, particularly for large tokamaks.

ISSN:0034-6748    

DOI:10.1063/1.1138200

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

A new experiment concept has been proposed for the shuttle/tethered satellite system missions, which can provide high‐resolution, global density mappings of certain ionospheric species. The technique utilizes bistatic LIDAR to take advantage of the unique dual platform configuration offered by these missions. A tuned, shuttle‐based laser is used to excite a column of the atmosphere adjacent to the tethered satellite, while triangulating photometric detectors on the satellite are employed to measure the fluorescence from sections of the column. The fluorescent intensity at the detectors is increased about six decades over both ground‐based and monostatic shuttle‐based LIDAR sounding of the same region. In addition, the orbital motion of the shuttle provides for quasiglobal mapping unattainable with ground‐based observations. Since this technique provides such vastly improved resolution on a synoptic scale, many important middle atmospheric studies, heretofore untenable, may soon be addressed.

ISSN:0034-6748    

DOI:10.1063/1.1138201

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Operation of a compact, corona‐preionized, XeCl excimer laser producing average output power in excess of 1 W at pulse repetition frequencies of up to 750 Hz is reported. This device is simple in construction and utilizes all commercially available components.

ISSN:0034-6748    

DOI:10.1063/1.1138202

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

An experimental apparatus, which simulates a subsonic multiple‐jet aerodynamic window, is fabricated and aerodynamic characteristics of the single‐curved jet and the multiple‐curved jets are studied. A nondimensional quantity &xgr; is introduced in order to represent the magnitude of the power consumption. Then, the effect of the window configuration on &xgr; is evaluated experimentally. Within the range of the present experiments, it is shown that the power consumption of the multiple‐jet aerodynamic window can be made less than that of the single‐jet scheme, if at least three stages of jets are utilized. It is also shown that the design of the window configuration is important to reduce the power consumption and to obtain the stable operation of multiple‐curved jets.

ISSN:0034-6748    

DOI:10.1063/1.1138203

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

A method has been developed for measuring the spatial profile of the output beam of an iodine laser at 1.315 &mgr;m, which requires only using two optical fibers, one for collecting a reference signal and the other for detecting the laser intensity at a given point of the wavefront. The precision is sufficient for laser engineering purposes.

ISSN:0034-6748    

DOI:10.1063/1.1138204

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

A simple fiber‐optic system for optical spectroscopy is demonstrated. It allows experiments to be performed at low temperatureswithoutanopticalDewar. This low‐cost apparatus is useful for a variety of optical experiments such as photoluminescence, reflectivity, and absorption, in addition to polarization measurements such as Faraday rotation. The main feature is an all‐glass system made from commercially available fiber‐optic cables and glass rods, andcontainsnofocusingoptics. Small diameter (<1 cm) sample holders are constructed that fit conveniently into storage Dewars or small diameter Dewars for high‐field magnets. Large diameter (few mm) flexible fiber bundles permit efficient coupling to inexpensive light emitting diode (LED) sources and to fiber‐optic illuminators. Fiber‐optic measurements of photoluminescence in Cd1‐xMnxTe,x=0.1, at high magnetic fields is illustrated.

ISSN:0034-6748    

DOI:10.1063/1.1138205

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

A magneto‐optical ellipsometer is described which uses polarization modulation and the longitudinal magneto‐optical Kerr effect. The ellipsometer allows a full determination of the optical and magneto‐optical constants of magnetic materials, as well as the registration of in‐plane hysteresis loops. The latter application is illustrated on a Ni80Fe20thin‐film sample.

ISSN:0034-6748    

DOI:10.1063/1.1138206

出版商:AIP    

年代:1985

数据来源: AIP