Ion source

An ion source, comprising:

• a shell defining an ionization chamber, a gas inlet, an electron input hole, and an ion output hole;
• an anode electrode located in the ionization chamber;
• and
• a field emission device located adjacent to the electron input hole, and comprising:
• an insulative substrate;
• an electron pulling electrode located on a surface of the insulative substrate;
• a secondary electron emission layer located on a surface of the electron pulling electrode;
• a first dielectric layer;
• a cathode electrode located apart from the electron pulling electrode by the first dielectric layer, wherein the electron pulling electrode is located between the insulative substrate and the cathode electrode, the cathode electrode has a surface oriented to the electron pulling electrode, and the cathode electrode has a first opening oriented to the electron input hole;
• and
• an electron emission layer located on the surface of the cathode electrode oriented to the electron pulling electrode.

An ion source, comprising:

• an insulative substrate;
• an electron pulling electrode located on a surface of the insulative substrate;
• a secondary electron emission layer located on a surface of the electron pulling electrode;
• a first dielectric layer;
• a cathode electrode located apart from the electron pulling electrode by the first dielectric layer, wherein the electron pulling electrode is located between the insulative substrate and the cathode electrode, the cathode electrode has a surface oriented to the electron pulling electrode, and the cathode electrode has a first opening;
• an electron emission layer located on the surface of the cathode electrode oriented to the electron pulling electrode;
• a gate electrode located apart from and insulated from the cathode electrode;
• a fourth dielectric layer located on a surface of the gate electrode and defining an ionization chamber oriented to the first opening;
• and
• an ion electrode located on the fourth dielectric layer.