Effect of a high-frequency field on the reflection of ion acousticwaves from the sheath at a grid |
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Authors: | Schott LW |
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Institution: | Dept. of Phys., Saskatchewan Univ., Saskatoon, Sask.; |
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Abstract: | Experiments are described which show that the reflection coefficient for ion acoustic waves (IAW) from the sheath at a grid is affected by an HF electric field with a frequency fHF≲5fpi(fpi =ion plasma frequency). For peak-to-peak amplitudes of the HF voltage drop across the sheath Φ0≲kB Te/e and fHF>f pi, the energy distribution of the ions passing through the grid develops a hot tail and the reflected wave suffers enhanced Landau damping. If Φ0≳kBTe/e and fHF<fpi, a large-amplitude IAW is excited at the grid; a well-defined ion beam is formed; and local growth of the reflected wave is observed. Test waves launched from the grid show the same propagation characteristics as the reflected waves |
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