摘要:

Based on the STALO (acronym for STAbilization of Local Oscillator) system wherein an external high Q cavity is used to frequency stabilize a reflex klystron, a technique was developed using a microwave Fabry‐Perot resonator (MFPR) operating at 35 GHz for performing time varying plasma diagnostics over a two to three order of magnitude range centered at 5×109electrons/cm3. Experimental results are given for 2 MHz density variations in a 125 &mgr; He rf induced discharge. The frequency response is an order of magnitude faster than an external feedback control system (also described) which utilizes the MFPR. Calibration techniques as well as the underlying theory are also given.

ISSN:0034-6748    

DOI:10.1063/1.1684271

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

A survey has been made on the temperature dependent behavior of several new types of carbon resistors and germanium sensors to determine whether any particular type might be suitable as a secondary thermometer in the 0.01–1.0 K temperature interval. Each thermometer was specially constructed to improve the thermal contact to the sensing element. Several commercial germanium and carbon resistance sensors appear promising as thermometers in the very low temperature interval. In addition, it appears feasible to extend the use of 0.02 at.% Au&sngbnd;Fe thermocouples down to 0.05 K.

ISSN:0034-6748    

DOI:10.1063/1.1684272

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

An electronic circuit breaker, designed to switch off the power to an electric motor when the mechanical load increases beyond the normal load, is described. The circuit operates rapidly and can sense an increase in mechanical load before it reaches destructive proportions. The sensitivity of the electronic circuit makes it necessary to incorporate a time delay that prevents the initial surge current from turning the motor off before it gets started.

ISSN:0034-6748    

DOI:10.1063/1.1684273

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

An approximation for the geometrical factor of cylindrical geometries which converges rapidly is found.

ISSN:0034-6748    

DOI:10.1063/1.1684274

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

A method for determining the polarization of a light source is to observe the transmitted light intensity through a polarizer set at two azimuthal positions with respect to any arbitrary axis. If the polarizer is mechanically rotated at a constant frequency, there are just four angular positions per revolution at which cross extinction occurs and onlyI∥or I⊥are transmitted. We have constructed a rotating polarizer in which eitherI∥or I⊥is transmitted independent of the azimuthal angle for nearly one‐half a cycle. Effectively, the transmitted light is square wave modulated with respect to two azimuthal positions of a stationary polarizer which differ by 90°. This rotating polarizer has been exceedingly valuable for precision and efficiency of polarization measurements where on‐line computer sampling of experimental data is used.

ISSN:0034-6748    

DOI:10.1063/1.1684275

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

A device is described which allows the stabilization of the output of a microwave source at power levels up to 1 W. Variations of the source power are reduced by more than 30 dB with a time constant of about 20 &mgr;sec. The long term stability of the device is better than 10−4over several hours. The device consists only of inexpensive commercially available components.

ISSN:0034-6748    

DOI:10.1063/1.1684276

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

A versatile electro‐optical shutter has been developed for use in optical pumping experiments. The shutter has a cutoff time of 25 nsec, a contrast ratio greater than 2×104to 1, can be held opened or closed for continuously variable amounts of time, and can effectively shutter light with a large angle of divergence (up to 8°). The shutter consists of a commercially built Kerr cell controlled by a high voltage modulator. The modulator is a specially designed bistable switch which is capable of producing variable width 31 kV pulses and can be cyclically operated up to 250 Hz. The high stability of the shutter together with its other properties makes it particularly useful in optical pumping experiments in which digital signal averaging techniques are used.

ISSN:0034-6748    

DOI:10.1063/1.1684277

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Modifications of a spark cutter are described which facilitate preparation of oriented mercury and alkali metal crystals having geometries suitable for ultrasonic experiments.

ISSN:0034-6748    

DOI:10.1063/1.1684278

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Given a resistive transducer which responds directly or indirectly to a physical quantityx, it is shown that the relationship may be linearized by linear methods if and only ifboththe resistance and conductance of the transducer are concave upward as functions ofx. This result applies to either deflection output or to null balance output. The application to the common temperature transducers is considered. It is shown that thermistors, linear metals (e.g., copper), and nickel can be linearized in terms of temperature, but platinum cannot be. If linearization is desired in terms of the reciprocal of absolute temperature, then all the above mentioned transducers can be linearized, including platinum. Quantitative results are obtained for all cases.

ISSN:0034-6748    

DOI:10.1063/1.1684279

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

We describe a cryostat which permits growth, and thermal neutron and visual examination of massive single crystals of the rare gas solids, their alloys, and other low melting point materials. Growth is from the melt at pressures up to 4 atm. Solids have been grown on a germanium substrate in an effort to preselect the desired lattice orientation. Temperature control is within a few hundredths of a degree for extended time intervals in a range of temperature from 65 to 230 K.

ISSN:0034-6748    

DOI:10.1063/1.1684280

出版商:AIP    

年代:1970

数据来源: AIP