摘要:

Recent improvements in cyclotron technique have led, in the case of the 37″ cyclotron at the University of California, to the utilization of beams of such intensity that nearly a kilowatt of power must be dissipated in the target. To maintain high operating efficiency it is desirable that targets should be bombarded in elementary form rather than as compounds, and that the cyclotron vacuum chamber should be protected from the debris of bombardment at all times. The former requirement puts a severe limitation on the designer because many elements are neither refractory nor are they good heat conductors. The second requirement necessitates that a thin metal window be used to isolate the target from the vacuum chamber, because most elements sublime or spatter in one way or another no matter how well cooled they may be. To meet this situation a bombarding chamber has been developed (a ``bell‐jar window''). It consists of a rectangular copper box with one end closed by a water‐cooled copper plate carrying the target and the other by a thin metal window. The window end is bolted to the cyclotron's target orifice and the interior of the box is filled with hydrogen or helium at a pressure of a few centimeters. The presence of the gas serves to keep the window cool, to keep the target from being damaged by the beam and to protect the cyclotron in the event of a sudden failure of the window. The metal windows are supported on a grid of elongated holes which has a geometrical aperture of about 93 percent. The target plate is heavily knurled and the element being bombarded may either be fused on it or pressed into the knurlings with a spatula. The surface of the target can further be protected by covering it with thin gold foil. With this arrangement it has been found possible to bombard red phosphorus, sodium metal, lithium metal and many other difficult targets with the full intensity of the cyclotron.

ISSN:0034-6748    

DOI:10.1063/1.1751532

出版商:AIP    

年代:1939

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1751533

出版商:AIP    

年代:1939

数据来源: AIP

摘要:

In designing electronic equipment for regulation of d.c. generators it is essential to know the effect on the regulated current or voltage of all possible variables in the regulating equipment as well as those in the generator proper. This paper presents, in the static case, a method of treatment which enables one to appraise quantitatively the importance of any source of possible instability in amplifier or generator. The method is applied to two types of regulating equipment, concerning which detailed information is included.

ISSN:0034-6748    

DOI:10.1063/1.1751534

出版商:AIP    

年代:1939

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1751535

出版商:AIP    

年代:1939

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1751536

出版商:AIP    

年代:1939

数据来源: AIP