摘要:

This paper, a guide to the literature, is directed to experimentalists planning to extend their research into the temperature range of 0.01–1 K. Included are discussions of refrigeration, thermal contact and isolation, thermometry, and several examples of how standard physical measurement techniques have been adapted to the temperature regime below 1 K.

ISSN:0034-6748    

DOI:10.1063/1.1136148

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A refrigeration process is described which enables the production of a sub‐&lgr;‐point4He temperatures without the production of superfluid. The advantages of the process for zero gravity (0‐g) and low‐noise refrigeration are described. The lowest temperature produced to date is 1.25 K. The process is also useful with other gases for refrigeration; the output temperature is selected by gas type.

ISSN:0034-6748    

DOI:10.1063/1.1136149

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A versatile low‐temperature apparatus for studies using ion beams in an ultrahigh vacuum environment is described. By providing variable‐temperature operation from ∼2–300 K, the facility can be used for a variety of studies. These have included low‐temperature ion implantations for the production of metastable superconducting systems, thermal‐annealing studies, and ion‐mixing experiments. The cryostat combines economical use of liquid helium, long‐holding time (several days) at liquid–helium temperatures as required for some studies, and ion–beam accessibility with the capability of absorbing high power (∼∼6 W at 5 K) for short periods. To allow adjustment of the target position relative to implanting or analyzing ion beams, the entire cryostat is mounted on a separate assembly providing vertical motion and rotation about the vertical axis.

ISSN:0034-6748    

DOI:10.1063/1.1136150

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Use of multichannel plate detectors has considerably extended the experimental techniques in atomic physics. In this context, a coincidence circuitry able to determine 64simultaneouscoincidence spectra is described. Use of fast electronic devices and separated amplifiers allows a high counting rate capability (5×105events per second) with a time resolution of 3.1 ns. UV photon‐scattered particle coincidence in He–He collisions is given as an example of the application of the present apparatus.

ISSN:0034-6748    

DOI:10.1063/1.1136151

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A significant improvement in the performance of the BNL Mark III magnetron negative ion sources has been achieved by putting cylindrical grooves on the cathode to geometrically focus surface produced H−and D−ions into the emission slit in the anode. The addition of these grooves has allowed us to reach desired negative ion emission current densities with an order of magnitude lower arc current than was previously required. An additional improvement in the operation of the magnetron has resulted from increasing the anode‐to‐cathode spacing in the back of the source, which facilitates ignition of the discharge at low pressures. The net result of these modifications has been an improvement in the gas and power efficiencies by at least a factor of three, and a reduction in the emittance of the beam.

ISSN:0034-6748    

DOI:10.1063/1.1136152

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

An experiment is described in which the picosecond temporal structure of a Cerenkov radiation source has been measured using an optical streak camera. Electrons in the Stanford Linear Accelerator Center (SLAC) three kilometer linear accelerator, bunched by the 2856 MHz acceleration fields, are used to generate Cerenkov radiation in a helium-filled gas cell. We show that it is possible to construct a Cerenkov cell which introduces subpicosecond time spread and allows for nondestructive monitoring of the electron beam.

ISSN:0034-6748    

DOI:10.1063/1.1136153

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A ZnO(Ga) scintillator has been developed which selectively detects 14 MeV neutrons in a large 2.5 MeV neutron and hard x‐ray background. The detector will be useful in measuring the 14 MeV neutron emission with trace concentrations of tritium in a predominately deuterium plasma during early experiments in the Tokamak Fusion Test Reactor (TFTR) or the Joint European Torus (JET).

ISSN:0034-6748    

DOI:10.1063/1.1136154

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A family of plasma guns supplying highly ionized carbon plasma is described. The guns are simple and inexpensive to construct and are pulsed by small capacitor banks of a few hundred joules. The output consists of 1017–1018multiply ionized carbon ions traveling at about 107cm/s. Neutral output is very low and arrives well after the ionized carbon. The guns and pulsers are very reliable.

ISSN:0034-6748    

DOI:10.1063/1.1136139

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Capacitively‐coupled transmission‐line voltage sensors and inductive‐shunt current sensors used in experiments with a high‐density gas‐embeddedzpinch have provided accurate and reliable measurements. Design and construction of these sensors is described, and their calibration is discussed in detail.

ISSN:0034-6748    

DOI:10.1063/1.1136140

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

In experiments involving pulsed high magnetic fields the appearance of the full induced voltage at the output terminals of large‐area inductive sensors such as diamagnetic loops and Rogowski belts imposes severe requirements on the insulation near the output. Capacitive detection of the inductive‐sensor output voltage provides an ideal geometry for high‐voltage insulation, and also accomplishes the necessary voltage division. An inductive‐shunt current monitor was designed to utilize the capacitive‐detection principle. The contruction of this device and its performance are described in this paper.

ISSN:0034-6748    

DOI:10.1063/1.1136141

出版商:AIP    

年代:1980

数据来源: AIP