摘要:

A very low‐pressure magnetically‐focused electron bombardment ion source is described which produces substantial quantities of ions in highly excited metastable states. Using the laser–fluorescence technique, we have measured a 2s3S1metastable content of 0.6%–2.3% in a 0.4 &mgr;A, 5 keV beam of7Li+. The source design can be applied to essentially any ionic species and offers the additional advantage of relatively low energy spread.

ISSN:0034-6748    

DOI:10.1063/1.1136566

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Plasma guns designed to provide high‐pulsed fluxes of ions for intense ion beam injectors are described. The guns use pulsed radial magnetic fields to accelerate ions longitudinally into magnetically insulated extraction gaps. Plasma was supplied using both spark sources and pulsed gas injection. In typical operation, a 1‐&OHgr; pulse of nitrogen ions with an ion flux equivalent to 50 A/cm2was produced. A variety of ions ranging in mass from protons to argon was investigated.

ISSN:0034-6748    

DOI:10.1063/1.1136567

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

A model of beam steering and beam collimation in tetrode extraction systems is presented which includes the effects of space charge in the interelectrode gaps. This model is compared with experiment in several geometries and shows that the inclusion of space charge allows better agreement to be obtained than in earlier theories.

ISSN:0034-6748    

DOI:10.1063/1.1136568

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

A method is proposed for improving the efficiency of cyclotron resonance heating of a toroidal plasma by ordinary mode radiation from the outside of the torus. Radiation not absorbed in the first pass is reflected from the inside of the torus by a corrugated surface which rotates the polarization by 90 °, so that a secondary source of extraordinary waves is created in the high field, accessible region of the plasma.

ISSN:0034-6748    

DOI:10.1063/1.1136569

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

The design and operation of a cryogenic pellet generator is described. The device is capable of producing spherical solid hydrogen pellets of sufficient size and repetition rate to meet prospective refueling requirements of near term tokamak fusion machines. It accelerates pellets to speeds in excess of 102m/s by gas dynamic drag techniques and has achieved initial injection into the APEX tokamak at Argonne National Laboratory. A discussion of gas dynamic drag acceleration techniques is presented with an evaluation of their significance to pellet acceleration technology.

ISSN:0034-6748    

DOI:10.1063/1.1136570

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

A quantitative statistical test for ascertaining the goodness of fit in deconvolution analysis is presented and is compared with two currently used tests. The new test is generally applicable and unlike the latter tests, still holds when significant random errors occur in both the measured excitation pulse and the measured luminescence curve. One of the existing tests involves a convenient, but subjective assessment of the randomness of a plot of weighted residuals and the new quantitative text is used to evaluate the scope of this subjective approach.

ISSN:0034-6748    

DOI:10.1063/1.1136571

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

The standard method of evaluating pulse–fluorometry measurements is to deconvolute the data using an experimentally determined excitation function. However, it is known that its determination may be inaccurate, because the instrumental response and the form of the exciting light pulse do vary with the wavelength. This may limit the accuracy of deconvolution and the confidence in its results. Therefore, in this paper an alternative evaluation method is suggested. The excitation function is not needed, if two independent measurements differing in the kinetics of the involved decays, but not in the excitation and emission wavelengths, can be performed. Those two measurements are sufficient to obtain the parameters of both decays.

ISSN:0034-6748    

DOI:10.1063/1.1136572

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

A new technique for measuring small displacements of piezoelectric‐driven mirrors has been applied to the calibration of piezoelectric‐driven mirror systems for laser resonator cavities. In this technique, a wave‐front sensor that includes an acousto–optic modulator and uses optical heterodyning measures the phase change when a mirror, driven by the piezoelectric translator, moves. Measurements obtained by means of this technique have been compared with measurements obtained with the traditional interferometer methods and have proven to be more precise. The increased precision was attributed to higher signal‐to‐noise ratios typically obtained with frequency‐modulated, relative to amplitude‐modulated, systems where intensity fluctuations exist in the system. The increased signal‐to‐noise ratio is advantageous when, as frequency increases, the output voltage from the driving power amplifier falls off. For a given amplifier, frequency–response data of the piezoelectric driver–mirror combination can be determined at higher frequencies. In this case, the frequency has been extended from 15–40 kHz.

ISSN:0034-6748    

DOI:10.1063/1.1136573

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

A thermionic diode with a shielded auxiliary compartment has been constructed to detect Doppler‐free two‐photon absorption. The shielded compartment prevents Zeeman and Stark broadening from external fields. The detector’s construction and mode of operation are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1136564

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Synchrotron radiation has recently contributed to the development of high‐resolution x‐ray microscopy either for biological investigations or for chemical microanalysis. Contact microscopy for this end appears to be particularly useful, but is mainly limited by the detectors that are used. In order to overcome these limitations—i.e., to obtain real time imaging and quantitative information—a study of a photoelectron x‐ray microscope is made. Contact configuration is used, but the usual detector is replaced by a thin photocathode. The emitted secondary photoelectrons are then imaged by a suitable emission electron microscope. Problems of photoemission, resolution, and D.Q.E. limitation are discussed. The particular nature of electron lens aberrations, due to photoemission characteristics, is taken into account. The conclusions are that resolutions down to 500 A˚ can be obtained in certain conditions. A preliminary low‐ magnification experiment is described and results are shown.

ISSN:0034-6748    

DOI:10.1063/1.1136565

出版商:AIP    

年代:1981

数据来源: AIP