Wire ion plasma gun

DETAILED DESCRIPTION OF THE INVENTION FIG.
1 illustrates the basic components of a plasma electron gun constructed in accordance with one embodiment of the present invention.
The gun includes an electrically-conductive grounded enclosure which is composed of a high voltage chamber 13, an ion plasma discharge chamber 12, and an electron transmissive foil window 2.
The wire 4 extends into or throughout plasma discharge chamber 12.
The foil window is electrically connected to the grounded enclosure, and it forms an anode which causes electrons to be accelerated to and through it.
The enclosure is filled to from one to 10 microns of helium.
A oathode 6 is positioned in the high voltage chamber 13 and insulated therefrom.
An insert 5 for the cathode is mounted on its lower surface.
The insert 5 is typically molybdenum, but can be any material with a high secondary emission coefficient.
The spacing between the cathode 6 and the enclosure is shaped to prevent Paschen breakdown of the electrical field.
A high voltage power supply 210 supplies a high negative potential of 150 to 300 kv to cathode 6 through cable 9, which extends through an epoxy insulator 14, to optional resistor 8 which is interposed between the cable 9 and the cathode 6.
The cathode 6 and insert 5 are cooled by an appropriate cooling liquid, such as an oil, which is pumped through conduit 7.
The plasma chamber 12 contains a number of metallic ribs 3 which are mechanically and electrically connected together.
The ribs 3 contain cutouts in the center to allow wire 4 to pass through the entire structure.
The sides of the ribs 3 facing the cathode 6 form an extraction grid 16, or the opposing side of the ribs form a support grid 15 for supporting the electron transmissive foil window 2.
Alternatively, extractor grids and anode plates can comprise sheets of metallic material with holes cut out therein.
Liquid cooling channels 11 provide for heat removal from the plasma chamber.
The electron transmissive window 2 may be composed of a one quarter to one mil thick titanium or aluminum foil, which is supported by the support grid 15 and sealed to the enclosure by an O-ring