Single grid focussed ion beam source

A process for forming a focussed beam of ions, comprising the steps of:

• forming a plasma of charged ions,
• extracting said ions from said plasma using a single flexible extraction grid having multiapertures therein, said extraction grid being located near said plasma and being comprised of an electrically conductive material, wherein said grid is sufficiently flexible to be bowed by electrostatic attraction of said plasma, and
• applying a potential to said grid which is negative with respect to the potential of said plasma, the voltage difference between said plasma and said grid being sufficiently great to cause bowing of said grid into a generally spherical shape, said grid focussing said extracted ions when bowed into said generally spherical shape.

A process for producing a focussed beam of ions, comprising:

• forming an ion plasma with an electron bombardment ion source including a cathode, and an anode located in a plasma discharge chamber,
• using a single flexible extraction grid having multiple apertures located at the end of said discharge chamber, said extraction grid being used to extract ions from said plasma, and
• applying a voltage potential to said grid which is negative with respect to ground and is different from the plasma potential, the voltage difference between said grid and said plasma potential being sufficient to bend said grid into a substantially curved shape, said extracted ions being focussed by said curved grid.

A method for forming a focussed beam of ions, comprising the following steps:

• forming an ion plasma with an electron bombardment ion source including an anode and a cathode located in a plasma discharge chamber,
• using a single flexible extraction grid having a multiple number of apertures therein to extract ions from said discharge chamber, said grid being located at the end of said discharge chamber and having an initial configuration which is substantially planar, and
• increasing the voltage difference between the voltage on said grid and the potential of the plasma to an amount sufficient to cause bowing of said grid to change its planar configuration to a generally curved configuration, said curved configuration causing focussing of the ions extracted from said plasma.

A method for forming a focussed beam of positively charged ions, comprising the steps of:

• forming an ion plasma in a plasma discharge chamber,
• applying an electrical potential to a flexible multiapertured grid located near the end of said discharge chamber to produce a potential difference between said ion plasma and said grid to extract ions from said chamber, and
• increasing the electrostatic attraction between said plasma and said grid by changing said potential difference to bend said grid thereby causing focussing of the ions extracted from said plasma, the amount of bending of said grid being dependent on the amount of electrostatic attraction it experiences.