Influence of the secondary electrons emitted by a cylindrical metal-dielectric structure on the Frankfurt 14 GHz electron cyclotron resonance ion source performances Rev. Sci. Instrum. 71, 918 (2000)Effect of secondary electron emission on sheath potential in an electron cyclotron resonance plasma A method has been devised for accurate determination of the absolute rate of sputtering, i.e., the measurement of the number of atoms liberated from a metallic target under the impact of a single ion of known energy. The accuracy of this measurement was 6 to 7 percent-a precision hereto unattainable by other methods. The apparatus producing argon ions consisted of a strong ion-source of capillary-arc type. The ions were accelerated within a high vacuum chamber through a potential, which was varied from 2000 to 7000 volts, and then allowed to strike a metallic target. The sputtering rate was determined by measuring the positive ion current to the target and the loss of target material. Results are given on sputtering of silver by argon, and on the secondary electron emission from aluminum and molybdenum.
Construction and operating characteristics of an ion source of the capillary arc type are described. The source yields 0.4 milliampere of singly charged argon ions through an orifice 1 mm in diameter, which allows, with pumping speeds of 14 liters per second, maintenance of a pressure of 5×10−5 mm Hg in the adjacent chamber where the ions are used. The ion beam is easily focused at ion accelerating voltages of 1000 to 6000 volts. The source has been used as part of an apparatus for study of controlled sputtering of metals bombarded by argon ions, and the accompanying secondary electron emission. The source can be used advantageously in a number of analogous researches of a fundamental character, and also has application in the field of engineering and biology.
Der Vorgang der Wieder~findung kurzer metalliseher Wechselstromliehtbogen, der als Durchschlag in stark ionisiertein Gase aufgefa~t werden kann, wird mittels Potentialmessungen in der Gasstrecke w~hrend des Strorrmulldurehganges untersucht. Der Vorgang spielt sieh ab in etwa 50-10 -6 sec. Die Potentialverteilung zeigt die Ausbildung einer Glimmentladung, die der neuen Bogenentladung vorhergeht, und den A~ffbau einer positiven Ratunladungsschieht an der jeweiligen Kathode der Entladung, von der die gesamte an den Bogenelektroden w.~hrend des Stromnulldurchganges auftretende Potentialdifferenz von einigen hundert Volt getragen wird; der Rest der Gasstrecke stellt dabei ein dem Bogenplasma ~hnliches Gas dar.
cuits. Handling of 3-circuit problems is remarkably simplified by this theory. It is generally assumed as applicable to all single-phase and polyphase circuits.According to the above elementary theory, if 2 secondaries have identical impedances with respect to the primary, their individual leakage impedances will be equal and their simultaneous shortcircuit currents will be equal and of the same power factor. Commonsense (uncritical commonsense) also would seem to demand such a conclusion, without any elaborate theoretical arguments. Recent experience has shown, however, that such is not necessarily the case in some polyphase transformers, and that particular attention to symmetry and the balancing of reactances may actually cause a large unbalance in load division. It is further found that such unbalance may change with change in the phase rotation of the excitation. Such anomalous behavior calls for a searching inquiry into the foundations of both theory and commonsense. May it not be that we have generalized too far?As an example, a transformer with a delta primary, and 2 oppositely zigzagged secondaries, is discussed in the paper and an explanation of the unexpected phenomena which results is given. Although it is not possible to anticipate the infinite variety of possible transformer connections involving interconnection of phases, the following general theorems are suggested :
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