Plasma acceleration from radio-frequency discharge in dielectric capillary

A capacitive rf discharge was demonstrated in a dielectric capillary for generation of quasineutral plasma flow with energies of several tens of eV. A potential gradient at the open end of the capillary and high-temperature electrons in the capillary discharge promote the ion acceleration. The plasma flow was generated from a ceramic capillary with inner diameter of similar to 0.8 mm and a length of similar to 10 mm, at a gas flow rate of 2-10 SCCM (SCCM denotes cubic centimeter per minute at STP) and input power of 15-20 W. The ion energy spectrum consists of high-energy accelerated ions and a low-energy tail formed due to ionization in the acceleration region. The relatively wide plume angle of similar to 65 degrees indicates that the acceleration region is placed outside the capillary and has a convex shape. Estimated total efficiency at 2 SCCM Xe flow rate and 15 W input power reaches 2%-3%. This approach may be attractive for micropropulsion applications due to its simplicity, low weight and small dimensions of the source, and the absence of a cathode neutralizer. (c) 2006 American Institute of Physics.