Session CO2 - Partially Ionized Plasmas and Applications.
ORAL session, Monday afternoon, October 29
Room 203 AB,
The Plasma Window is a novel apparatus that utilizes a stabilized plasma arc as an interface between vacuum and atmosphere without solid material. In addition to sustaining a vacuum atmosphere interface, the plasma window has a lensing effect on charged particles. The plasma current generates an azimuthal magnetic field, which exerts a radial Lorentz force on charged particles moving parallel to the current channel. With proper orientation of the current direction, the Lorentz force is radially inward. This feature can be used to focus beams to a very small spot size, and to overcome beam dispersion due to scattering by atmospheric atoms and molecules. Consequently, for a number of particle beam applications, the plasma window is an attractive alternative to differential pumping. Two such applications are non-vacuum electron beam welding and hypersonic wind tunnel heating. Design issues that are presently under consideration involve electron beam optics due to plasma window lensing effects, and preventing ions and electrons from entering the beam structure. Matching electron beam columns to plasma windows while shielding accelerating and focusing elements from plasma particles to prevent breakdowns is to be discussed in the presentation.