| 摘要 |
<p>A .gamma.-mode, resonant-cavity plasma discharge (18) that can be operated at atmospheric pressure and near room temperature using 13.56 MHz rf power is described. Unlike plasma torches, the discharge produces a gas-phase effluent no hotter than 250 ~C at an applied power of about 300 W, and shows distinct non-thermal characteristics. In the simplest design, two concentric cylindrical electrodes (14, 20) are employed to generate a plasma in the annular region therebetween. A "jet" of long-lived metastable and reactive species (22) that are capable of rapidly cleaning or etching metals and other materials is generated which extends up to 8 in. beyond the open end of the electrodes (14, 20). Arcing is prevented in the apparatus by using gas mixtures containing He, which limits ionization, by using high flow velocities, and by properly shaping the rf-powered electrode (14). Because of the atmospheric pressure operation, no ions survive for a sufficiently long distance beyond the active plasma discharge to bombard a workpiece, unlike lowpressure plasma sources and conventional plasmas.</p> |
