摘要:

A Cs vapor target is described that uses a surface ionization detector inside the target chamber for direct Cs density determination and whose length is variable, permitting variation of the target thickness at constant target density. By use of a variable length target, accurate cross sections are determined that do not require knowledge of the ’’effective’’ target length. Sample cross section data obtained using this target are shown for electron capture by H+and H0and electron loss by H−in Cs vapor at 1000 eV.

ISSN:0034-6748    

DOI:10.1063/1.1136069

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Measurements of the effective absorption coefficient &mgr; have been made, for a range of neutron energies, of large single crystal specimens of quartz, silicon and sapphire, at 300 K and 80 K. The effectiveness of such filters is given by the ratio of &mgr; for (unwanted) epithermal neutrons to that for the desired thermal neutron beam. Our results indicate that sapphire is significantly more effective than either quartz or silicon for a wide range of neutron energies.

ISSN:0034-6748    

DOI:10.1063/1.1136070

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A CO2laser interferometer is used for measuring the average free electron density along a vertical path in Doublet III, a large fusion research tokamak. The CO2laser is used together with a colinear HeNe laser to form a two wavelength interferometer which is capable of measuring plasma fringe shifts which are much less than the fringe shifts due to mechanical vibrations. This diagnostic has been shown to be able to resolve plasma electron fringe shifts smaller than 1/17 of a fringe during the pulsed operation which causes mechanical motion resulting in as many as 10 fringe shifts. The interferometer is operated in the Michelson configuration with a total double path length through the plasma of 6 m. The density resolution then is better than 2×1012cm−3. A density resolution of about 0.5×1012cm−3has been achieved during relatively quiet operation.

ISSN:0034-6748    

DOI:10.1063/1.1136071

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A homodyne method proposed for detecting asymmetric spectra encountered in scattering experiments is examined theoretically and experimentally. The experiments are carried out on a simulated electrical circuit, and the validity of the proposed method is demonstrated. Various kinds of error in spectra obtained by the proposed homodyne method are examined and identified.

ISSN:0034-6748    

DOI:10.1063/1.1136072

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A modified Thomson parabola ion spectrometer of a wide dynamic range for studies of flash ions emitted from laser produced plasmas was developed. The exact velocity distributions of different ion species were obtained separately with sufficient velocity resolution.

ISSN:0034-6748    

DOI:10.1063/1.1136073

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

The steering of ion beamlets by aperture displacement in two‐stage four‐grid accelerators is examined using a model previously developed for single‐stage three‐grid accelerators with large acceleration‐deceleration ratio. The analysis (which includes the second order effects of space charge and the effect of potential sag due to finite aperture radius) is shown to be in good agreement with experimental data from two‐stage accelerators.

ISSN:0034-6748    

DOI:10.1063/1.1136074

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

The azimuthal and axial velocity of the source‐sink flow in a rapidly rotating cylinder were measured by using the back scattered mode of the laser‐Doppler velocimeter. A rotating optical system was devised for measuring the gas flow with a high angular velocity of 5.2×102rad/s. The incident laser beams were introduced into the cylinder through the rotating optical system which synchronously, but independently, rotating with the cylinder. The Doppler‐shifted signal was observed from the light back‐scattered by small paraffin mist particles of about 1 &mgr;m in diameter. The accuracies of the measurements were within ±5% for the azimuthal flow‐velocity component and ±8% for the axial one. TheE1/4layers formed on the sidewall and the feed radius were clearly observed due to the small Ekman numberE=2.2×10−5. The theoretical results (boundary layer theory and numerical calculation) agree quantitatively with the experimental ones, except in the case of the feed radius.

ISSN:0034-6748    

DOI:10.1063/1.1136075

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

We describe the construction of optical scattering cell which has been used for the Brillouin spectroscopy of ferroelastic KH3(SeO3)2. Using a pneumatic transducer, we were able to obtain uniaxial stress up to 18 MPa in a 4 mm cube sample. Temperatures down to liquid N2and up to 60 °C are obtainable with the stability of 2 mK. The cell is constructed for 90 degrees scattering geometry and allows the use of index matching liquid.

ISSN:0034-6748    

DOI:10.1063/1.1136076

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A high field pulsed magnet system with its associated electronics has been modernized to obtain a device which is easy to use. The magnet has been synchronized to operate with an optical multichannel analyzer; the coil has been miniaturized and tested with success in a pumped conventional dewar with liquid helium and in a tube with flowing gaseous helium. Fields of 20Thave been obtained above 77 K and 14.2 T below that temperature.

ISSN:0034-6748    

DOI:10.1063/1.1136077

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A thermally stable double beam laser interferometer for the measurement of mechanical strains due to domain switching in ferroelectric materials is described. Sample sizes vary from 0.25 mm to 5 mm in thickness, and maximum strains produce from 1 to 50 fringes in the data. A quadrature detection scheme provides the resolution which is required to interpolate accurately the fringe record and determine the direction of surface mechanical displacement. Specific sample mounting techniques are also developed in order to attain well‐defined loading conditions. Two sample holders, one for mounting very thin discs and the other for 5 mm cubes, are described. They induce minimal mechanical loadings on the samples. Typical data exhibiting the effects of domain switching due to an applied electric field are shown for the hot‐pressed ceramic PZT 65/35.

ISSN:0034-6748    

DOI:10.1063/1.1136078

出版商:AIP    

年代:1980

数据来源: AIP