The eective secondary electron yield in the space-charge limited condition
نویسندگان
چکیده
The dependence of the eective secondary electron yield on the potential distribution and the target materials was investigated by means of electron transport simulation in the sheath with the potential distribution calculated for the dierent emission characteristics of Be (Z 4), C (Z 6), Mo (Z 42) and W (Z 74) as the target materials. For lower primary energy incidence the eective secondary electron yield in the space-charge limited condition (SCLC) is markedly suppressed due to the prompt return of the secondary electrons. For higher energy electrons, the yield is independent of the potential distribution in the sheath and the energy distribution of the emitted electrons is shifted to higher energy direction. This eect would increase the sheath potential resulting in the increase of both ion energy ̄ux to the surface and sputtering yield. Because of their high re ̄ection coecients this result should be very important for high Z materials but not for low Z materials. Ó 1998 Elsevier Science B.V. All rights reserved.
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