ABSTRACT Results obtained from the eigenvalue perturbation method and Monte Carlo calculations are discussed. It is noted that the space-charge waves experience a growth during the latter part of the beam trajectory in the first half cycloid before the beam enters the interaction region. From the formula for the diocotron gain for a beam between two conducting planes, it is shown that diocotron gain is maximum when the beam is placed symmetrically with respect to the two conducting planes and is reduced to zero value when the beam position approaches either of the two conducting planes. Some further considerations for diocotron gain reduction are discussed. These results are in agreement with the experimental results. It is shown that the growth noticed in the earlier methods is essentially due to the diocotron gain during the latter part of the beam trajectory in the gun region. For low noise operation, a virtual elimination of the latter part of the gun region in the short Kino gun and a modified short ...
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