Ion beam extraction apparatus and method for creating an ion beam

1 . An ion beam extraction apparatus, being configured for creating an ion beam, comprising

an ion source device being arranged for creating ions, and

a grid device comprising at least two grids including:

a plasma grid arranged next to the ion source device and being the first grid passed by the ions created by the ion source device, and

an extraction grid arranged adjacent to the plasma grid,

said at least two grids being arranged adjacent to the ion source device and having a mutual grid distance along a beam axis, wherein

the grids are electrically insulated relative to each other,

the grids are arranged for applying different electrical potentials for creating an ion extraction and acceleration field along the beam axis, and

the ion source device and the grid device are arranged in an evacuable ion beam space extending along the beam axis, wherein

the plasma grid is a movable grid, which can be shifted along the beam axis,

the extraction grid has a fixed distance from the ion source device,

the grid device is coupled with a grid drive device, and

the grid drive device comprises a drive motor, which is arranged for moving the plasma grid along the beam axis and setting the mutual grid distance between the plasma grid and the extraction grid, and

a cooling device with cooling medium supply lines coupled to the grids and arranged for cooling the grid device.

2 . The ion beam extraction apparatus according to claim 1 , wherein

the plasma grid has a grid support frame, which is shiftable along linear guide carriers extending parallel to the beam axis, and

the drive motor is coupled with the shiftable grid support frame.

3 . The ion beam extraction apparatus according to claim 2 , wherein

the grid drive device comprises at least one pair of a rotating spindle nut and a drive spindle, which is coupled with the shiftable grid support frame, and

the spindle nut is rotatable by the drive motor.

4 . The ion beam extraction apparatus according to claim 3 , wherein

the grid drive device comprises multiple pairs of spindle nuts and drive spindles, which are coupled with the shiftable grid support frame at different edge sections thereof.

5 . The ion beam extraction apparatus according to claim 4 , wherein

the drive spindles comprise one primary drive spindle which is directly coupled with the drive motor and at least one secondary drive spindle which is coupled with the primary drive spindle via a chain or belt drive.

6 . The ion beam extraction apparatus according to claim 3 , wherein

the drive motor is a pressurized air motor.

7 . The ion beam extraction apparatus according to claim 1 , wherein

the drive motor is arranged in a surrounding outside of the evacuable ion beam space, and

the drive device is coupled with the plasma grid using membrane bellows for vacuum sealing.

8 . The ion beam extraction apparatus according to claim 1 , further comprising

a position measurement device being arranged for sensing a position of the plasma grid.

9 . The ion beam extraction apparatus according to claim 8 , wherein

the position measurement device comprises at least one of a drive monitor coupled with the grid drive device and a position sensor coupled with the plasma grid.

10 . The ion beam extraction apparatus according to claim 8 , further comprising

a grid position control unit being coupled with the grid drive device and the position measurement device and being configured for a loop control of setting the grid distance.

11 . The ion beam extraction apparatus according to claim 1 , further comprising

a mechanical stop arrangement being arranged for limiting a range of setting the grid distance.

12 . The ion beam extraction apparatus according to claim 1 , wherein

the ion beam extraction apparatus is configured as a neutral beam injection apparatus of a fusion plasma plant, wherein

the ion source device is a plasma source with an ion exit window, and

the plasma grid is arranged at the ion exit window of the plasma source and the extraction grid is coupled with a high voltage power supply.

13 . The ion beam extraction apparatus according to claim 1 , which is configured for use as

a neutral beam injection apparatus of a fusion plasma plant,

an ion generator of an ion implantation plant,

an ion generator of a coating plant,

an ion generator of a medical application, or

an ion thruster.

14 . A method of creating an ion beam along a beam axis, wherein an ion beam extraction apparatus according to claim 1 is used, comprising

creating ions with the ion source device, and

passing the ions through the ion extraction and acceleration field along the beam axis, wherein the ion extraction and acceleration field is created with the grid device comprising the plasma grid and the extraction grid, wherein

the ion source device and the grid device are arranged in the evacuated ion beam space extending along the beam axis, wherein

the grid device is adjusted by moving the plasma grid along the beam axis, wherein the grid distance is set by the grid drive device which is coupled with the grid device.

15 . The method according to claim 14 , wherein

the grid distance is set such that particle energy can be chosen independently from particle current at simultaneously minimum divergence.

16 . The method according to claim 14 , wherein

the grid distance is set using a loop control in dependency on a power parameter of the extracted ion beam.