Electron beam emitter

1. An exit window for an electron beam emitter through which electrons pass in an electron beam, the exit window comprising:

a first window layer comprising foil having a series of holes formed therein; and

a second window layer extending over the first window layer, said second window layer extending over the holes of the first window layer providing thinner window regions which allow easier passage of the electrons through the exit window.

2. The exit window of claim 1 in which the first window layer foil comprises a material selected from the group consisting of titanium, beryllium, aluminum, stainless steel, copper, gold and silver.

3. An electron beam emitter comprising:

a vacuum chamber;

an electron generator positioned within the vacuum chamber for generating electrons; and

an exit window on the vacuum chamber through which the electrons exit the vacuum chamber in an electron beam, the exit window comprising a first window layer comprising foil having a series of holes formed therein, and a second window layer extending over the first window layer, said second window layer extending over the holes of the first window layer providing thinner window regions which allow easier passage of the electrons through the exit window.

4. The emitter of claim 3 further comprising a support plate for supporting the exit window, the support plate having a series of holes therethrough which are aligned with holes of the first window layer.

5. The emitter of claim 4 in which multiple holes of the first window layer are aligned with each hole of the support plate.

6. The emitter of claim 3 in which the first window layer foil comprises a material selected from the group consisting of titanium, beryllium, aluminum, stainless steel, copper, gold and silver.

7. A method of forming an exit window for an electron beam emitter through which electrons pass in an electron beam comprising:

providing a first window layer comprising foil;

forming a second window layer over the first window layer; and

forming a series of holes through the first window layer to provide thinner window regions where said second window layer extends over the holes of the first window layer which allow easier passage of the electrons through the exit window.

8. The method of claim 7 further comprising forming the first window layer foil from a material selected from the group consisting of titanium, beryllium, aluminum, stainless steel, copper, gold and silver.

9. A method of forming an electron beam emitter comprising:

providing a vacuum chamber;

positioning an electron generator within the vacuum chamber for generating electrons; and

mounting an exit window on the vacuum chamber through which the electrons exit the vacuum chamber in an electron beam, the exit window comprising a first window layer comprising foil having a series of holes therethrough, and a second window layer extending over the first window layer, said second window layer extending over the holes of the first window layer providing thinner window regions which allow easier passage of the electrons through the exit window.

10. The method of claim 9 further comprising mounting the exit window on a support plate, the support plate having a series of holes therethrough which are aligned with holes of the first window layer.

11. The method of claim 10 further comprising aligning multiple holes of the first window layer with each hole of the support plate.

12. The method of claim 9 further comprising forming the first window layer foil from a material selected from the group consisting of titanium, beryllium, aluminum, stainless steel, copper, gold and silver.