An X-ray generator includes a cathode having an emitter made of carbon nanotubes which emits electrons by field emission and thus becomes a cold cathode electron emission source. In the invention using the carbon nanotubes, any one of the following three forms is adopted to control the tube current apart...http://www.google.com.au/patents/US6456691?utm_source=gb-gplus-sharePatent US6456691 - X-ray generator
