Electron sheaths form near the surface of objects biased more positive than the plasma potential, such as a Langmuir probe collecting electron saturation current. Generally, the formation of electron sheaths requires that the electron-collecting area be sufficiently smaller ( m M 2.3 e times) than the ion-collecting area. They are commonly thought to be local phenomena that collect the random t...

Elongated dust grains exist in astrophysical plasmas. Anisotropic growth of elliptical dust grains, via plasma deposition, occurs if the deposited ions are non-inertial. In reality the extent of such growth depends upon the initial kinetic energy of the ions and the magnitude of the electric field in the sheath. Simulations of the dynamics of the ions in the sheath are reported, showing how ell...

Abstract Precise control of the particle motion in externally applied electric and magnetic fields is great significance development E × B source to generate high-density plasma deliver a stable ion beam current. Especially, Penning discharge source, heating energy relaxation electrons concentrated column along field line. Plasma researchers have thus far focused on relevant physical phenomena ...

In this study cauda epididymal spermatozoa of rats maintained on a selenium-deficient diet for 5 and 7 months exhibited an array of flagellar defects. Spermatids and spermatozoa were analyzed by light and electron microscopy to define the appearance of flagellar abnormalities during spermiogenesis and post-testicular sperm development. Late spermatids of selenium-deficient rats displayed normal...

In fusion negative ion sources, the negative ions are formed on the caesiated plasma grid predominantly by hydrogen atoms from the plasma. The space charge of the negative ions leaving the wall is not fully compensated by incoming positive ions and at high enough emission a virtual cathode is formed. This virtual cathode limits the flux of negative ions transported across the sheath to the plas...

An experiment is described in which monodisperse dust grains are levitated within a dc sheath above a conducting plate in argon plasma. For plate bias voltages that are not too negative ~>210 electron temperatures!, the observed dust levitation heights are near to values calculated from a model combining equations for the sheath with those for grain charging. When the plate is more negatively b...