(Jimmy of the Clue Crew reports from the Stanford Linear Accelerator at Menlo Park, CA.) At one end of the accelerator, particles are fired out of a gun that uses this type of negative electrode, just like the ray on your TV set
... 
meable conductive cover, preferably of the mesh type, ... and an accelerator 
electrode system for creating an elec ... of a variable negative potential to the 
apertured control.