摘要:

A simple matrix optic theory of multipass laser interferometers shows how a relatively vibration proof system can be easily set up. Measurements made with such systems of the decay of a helium plasma are presented.

ISSN:0034-6748    

DOI:10.1063/1.1685317

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

A method is described for determining spot size and intensity distribution of a low powered laser by use of inexpensive components normally found in an optics laboratory. The method is useful for routine performance checks of laboratory lasers and as a tool for adjusting focus in optical systems.

ISSN:0034-6748    

DOI:10.1063/1.1685318

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

A new ultrasonic interferometer for the automatic measurement of transit times is described. Its main advantage is its ability to follow very large changes of the transit time (1–20) and still maintain a resolution of typically 2.5×10−10sec. The method is based on the phase sensitive detection of multiple echoes, counting of the output signal at the rate of four counts per full cycle, and an additional interpolation.

ISSN:0034-6748    

DOI:10.1063/1.1685319

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

The steady state gain of electron space current in straight continuous channel electron multipliers is calculated. Ion feedback and space charge effects are neglected, but variation of secondary yield with primary energy and increased wall conductivity due to electron bombardment are considered. Saturation occurs when enough wall current is converted to space current so that the reduced electric field diminishes the effective secondary yield to unity. Predicted results are in good qualitative agreement with reported observations.

ISSN:0034-6748    

DOI:10.1063/1.1685320

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

An rf induction‐heated furnace has been designed that produces a stable linear temperature gradient greater than 1000° C/cm and a maximum specimen temperature of 2000°C. Methods of measuring temperature in a temperature gradient have been evaluated and the performance of the furnace and its power requirements are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1685321

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

Fluid flow temperature controllers may be used as general purpose laboratory instruments if sufficient flow rate, control flexibility, and ease of design and fabrication are provided. Performance of 220°C/min slew rate and ±0.25°C dead band over the range −180 to 90°C is readily attainable from the instrument with nitrogen gas flows of 60 liters/min when liquid nitrogen is used as heat sink and boiling water as heat source.

ISSN:0034-6748    

DOI:10.1063/1.1685322

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

A scintillation detector system is described which can be used for dynamic diffraction studies. This system contains several individual channels with each channel (consisting of a scintillator, light pipe, and photomultiplier tube) positioned at a unique 2&thgr; position; thus, measurement of diffracted intensity vs 2&thgr; can be made. Signal‐to‐background ratio for the (200) reflection of powdered LiF using copper radiation was measured to be 3.0. Angular resolution depends upon the scintillator size and proximity to the x‐ray source. For a four‐channel system used in x‐ray diffraction studies of material undergoing shock wave compression [Q. Johnson, A. Mitchell, R. Keeler, and L. Evans, Phys. Rev. Lett. 25, 1099 (1970)] angular resolution was about 1° in 2&thgr;. This resolution can be increased by methods which increase signal strength.

ISSN:0034-6748    

DOI:10.1063/1.1685323

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

This paper presents the description of a wall‐stabilized arc device capable of producing the emission lines of metals in a cylindrically stable configuration. An unconventional method of viewing the arc and microphotometer tracings of the photographs of arc discharge as proofs of its symmetry is also discussed. A highly resolved Fabry‐Perot recording of the emission line of Cu I at 5153 Å shows the constant emission characteristic of this device.

ISSN:0034-6748    

DOI:10.1063/1.1685268

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

An optical readout system for the analysis of laser Doppler velocimeter (LDV) signals is described and test results are given. The signal from the LDV is displayed on a TV screen and recorded photographically. The photographic negative is placed in a Fourier transform optical system which displays the frequency spectrum of the negative on a screen or photographic material. Flow velocities are then calculated from the frequency values displayed by the system and these velocities are shown to agree very closely to velocity measurements made simultaneously using a Pitot tube.

ISSN:0034-6748    

DOI:10.1063/1.1685269

出版商:AIP    

年代:1971

数据来源: AIP

摘要:

A system was developed for producing repetitive short bursts of preferentially oriented spin polarized neutrons for magnetic investigations utilizing neutron spectroscopy. A continuous stream of polarized neutrons from a reactor‐monochromator combination is passed through a region in which periodic inversion of polarization is effected by continuous application of an rf field at the Larmor frequency perpendicular to a pulse modulated dc magnetic field. A novel circuit for fast transition modulation of the dc field permits currents as high as 1 A to be switched in less than 2 &mgr;sec in the 6 mH dc coil. The maximum burst repetition rate is approximately 83 300 pulses/sec.

ISSN:0034-6748    

DOI:10.1063/1.1685270

出版商:AIP    

年代:1971

数据来源: AIP