Improvements in and relating to coating processes

A method of depleting a plasma in a plasma coating apparatus of electrons, the plasma coating apparatus comprising apparatus comprising a target, the method comprising the steps of:

• generating a plasma comprising ions, particulate material and electrons adjacent the target using an electric power source, which biases the target, and by using a magnetic arrangement to form a magnetic field in the vicinity of the target, the magnetic field comprising a plasma trap being a region of relatively high magnetic field strength, which confines a plasma generated thereby to a region adjacent the target, the plasma trap having an outer boundary layer where the relatively high magnetic field strength inside the boundary layer drops-off rapidly as a function of distance from the target;
• and
• characterised by depleting the plasma of electrons by:
• providing a magnetic field that is superimposed over the magnetic field of the plasma trap and which extends beyond the boundary layer of the plasma trap, which draws electrons from, or near to, the boundary layer of the plasma trap away from the target;
• and by applying a baseline voltage to the target;
• and
• applying periodic voltage pules to the target.

A system comprising:

• two or more plasma coating devices, each device comprising:
• a target;
• means for generating a plasma adjacent the target, the plasma comprising ions, particulate material and electrons;
• and
• an electron depletion device;
• wherein at least one pair of the plasma coating devices are at least one of mirrored and opposing.