Speaker
Description
Although fundamental in many technologies, the physics of arcs is not completely understood, since unambiguous experiments are limited by physical access, unpredictability and short time scales. Unipolar arc tracks showing arc motion have been seen in several tokamaks (but the arcs seem to move in the opposite direction from that expected from J x B forces). There has been little data on arc motion in rf cavities, since the phenomenon is even less accessible there, however images of field emission from the irises of an 805 MHz cavity in a 3 T magnetic field seem to show field emitters exhibiting circumferential motion around the cavity axis. Limited data showed that, in the absence of strong magnetic fields, field emitters did not move. We discuss modeling and experiments that would improve our understanding of these phenomena.
