Magnetic and Collisional Effects on Presheaths
2008.01.03 10:27
연도 | 1995 |
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저널명 | Physics of Plasmas |
쪽 |
The effects of both magnetic field and collisions on presheath properties are experimentally
investigated in plasmas with electron temperatures much greater than ion temperatures.
Measurements of plasma potential in collisionless plasmas show presheath thicknesses at
boundaries oblique to magnetic field to be approximately (C,lw,;)sin I+$ where C, is the ion sound
speed, wci is the ion gyrofrequency, and ‘4’ is the angle between the magnetic field and the normal
to the wall boundary. Measurements of plasma potential in collisional plasmas find presheaths
consisting of two distinctive regions. With ion-neutral collision mean-free path A,<( C,/w,i)sin ~4,
the presheath region next to the sheath has collisional characteristics and a thickness of
approximately (0.5 - 0.6)h, . The corresponding presheath region adjacent to the bulk plasma has
magnetic characteristics and a thickness of approximately (0.5 - 0.9) (C,lW,i) sin $. Equipotential
contours in the collisional region of this presheath are found to be parallel to the boundary, while
those in the magnetic region are not.