Pulsed ion beam source
AssigneeSandia Corporation
InventorJohn B. Greenly
Life of this patent
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Abstract
An improved magnetically-confined anode plasma pulsed ion beam source. Beam rotation effects and power efficiency are improved by a magnetic design which places the separatrix between the fast field flux structure and the slow field structure near the anode of the ion beam source, by a gas port design which localizes the gas delivery into the gap between the fast coil and the anode, by a pre-ionizer ringing circuit connected to the fast coil, and by a bias field means which optimally adjusts the plasma formation position in the ion beam source.
Claims55
A pulsed ion beam source comprising:
- means for delivering a gas puff to a first gap between fast magnetic field means for forming a fast magnetic field and anode electrode means, the fast magnetic field fully ionizing the gas puff to produce a plasma and moving the resulting plasma into an accelerating gap between the anode electrode means and cathode electrode means;
- means for forming a magnetically insulated accelerating gap for passing the plasma comprising means for forming a slow magnetic field, said slow magnetic field means being located proximate to the cathode electrode means;
- wherein the fast and slow magnetic fields intersect to define a separatrix region where the plasma is on a flux surface that eliminates beam rotation and
- means for delivering a positive electric charge pulse from a power source to the anode electrode means for the purpose of accelerating ions in the plasma from the separatrix region towards a target.
A magnetically confined anode plasma source for generating an ion beam having little or no rotation, said plasma source comprising:
- a cathode assembly having a cathode electrode and an associated slow magnetic coil field for generating a magnetic flux having a first profile;
- an anode assembly having an anode electrode and an associated fast magnetic field coil for generating a magnetic flux having a second profile, said first and second magnetic flux profiles having a separatrix when said slow and fast magnetic field coils are energized;
- wherein said cathode electrode and anode electrode form therebetween an ion acceleration gap and wherein the separatrix between said first magnetic flux profile and said second magnetic flux profile is disposed in said acceleration gap adjacent to said anode electrode.
A magnetically confined anode plasma source for generating an ion beam comprising:
- an anode assembly including an anode electrode having an associated fast driving coil;
- a cathode assembly including a cathode electrode and an associated slow driving coil, said anode electrode and cathode electrode forming therebetween an ion acceleration gap;
- a gas valve assembly associated with said anode assembly, said gas valve assembly including a supersonic gas delivery nozzle for delivering a localized volume of gas to a region adjacent to said fast driving coil, said gas volume, as delivered to said region, being essentially free of flow components transverse to said acceleration gap.
A magnetically confined anode plasma source for generating an ion beam comprising:
- an anode assembly including an anode electrode and an associated fast driving coil;
- a cathode assembly including a cathode electrode and an associated slow driving coil, said anode electrode and cathode electrode defining therebetween an ion acceleration gap;
- a gas valve assembly for introducing a volume of gas into a region adjacent said fast driving coil upstream of said acceleration gap;
- a fast coil energizing circuit including a voltage source, switchably connected to said fast driving coil, for ionizing the gas to form a plasma and for adjusting the magnetic field between the fast driving coil and the anode electrode to thereby position the volume of plasma with respect to the accelerating gap.
A pulsed magnetically confined anode plasma source for surface treatment comprising:
- an anode assembly including an anode electrode and an associated fast driving magnetic coil;
- a cathode assembly including a cathode electrode and an associated slow driving magnetic coil, said anode electrode and cathode electrode forming therebetween a diode having an ion acceleration gap, said slow driving magnetic coil forming a diode insulating magnetic field in said plasma acceleration gap;
- a gas valve assembly for introducing a volume of gas into a region adjacent said fast driving coil;
- an inductively produced electric field producing source for ionizing said gas into a plasma;
- and
- a pulsed power source connected to said anode assembly for accelerating ions from said plasma to form an extractable ion beam, said anode electrode being configured to shape the magnetic flux from the fast driving and slow driving coils whereby said ion beam is extracted with little or no rotation.
A method of generating an ion beam using a magnetically confined anode plasma ion source comprising a vacuum chamber having an anode assembly including an anode electrode and a fast driving coil and a cathode assembly including a cathode electrode and a slow driving coil, the anode electrode and cathode electrode defining therebetween an acceleration gap, said method comprising the steps of:
- (a) introducing a puff of gas into said vacuum chamber to produce a localized volume of gas adjacent said fast driving coil but insulated from said fast driving coil;
- (b) pre-ionizing said gas using said fast driving coil;
- (c) further ionizing said gas while moving said gas away from said fast driving coil to create a thin, magnetically confined plasma layer;
- (d) applying a pulsed power signal to said anode electrode to form an ion beam from said plasma;
- and
- (e) extracting said ion beam essentially without rotation thereof.
Dependencies are inferred from the claim text.