Compact Plasma and Focused Ion Beams

91

6

Plasma Production in Continuous-Mode

Microwaves: Rectangular Nonmulticusp

Waveguide

Introduction

In Chapter 5, we have seen that a plasma could be produced in a near-circu-

lar multicusp waveguide with a dimension smaller than the cutoff value. In

a waveguide with a multicusp magnetic eld, the eld lines are arched along

the circumference connecting poles of opposite polarity, as shown sche-

matically in Figure 6.1a. On the other hand, the electric eld of the circular

mode (TE

11

) is peaked at the center and curved radially outward as shown

in Figure 6.1b. Therefore, when waves are launched into a circular multicusp

waveguide, the electromag ...