# US 4,395,631 A · High density ion source

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- Number: US 4,395,631 A
- Document ID: US4395631A
- Status: Granted
- Kind: A
- Application number: 06/085,261
- Filed: 1979-10-16
- Granted: 1983-07-26
- Earliest claimed: 1979-10-16
- Assignees: Occidental Research Corporation
- Inventors: Winfield W. Salisbury
- Web page: https://patentgrep.com/patent/US4395631A

## CPC

- H01J 27/02: Ion sources; Ion guns {(for examination or processing discharge tubes H01J37/08; ion sources, ion guns for particle spectrometer or separator tubes H01J49/10; ion propulsion F03H1/00)}
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)

## Abstract

A source for a high density electrically neutral beam of combined positive and negative particles suitable for bombardment and heating of a pellet of nuclear fusion material to fusion temperature. A source mounted in a housing with a spherical substrate having positive ion emitter material thereon, first, second and third grids spaced from each other along the beam path, and electron emitters, for providing positive ion beams and electron beams at the same velocity for mixing to provide an overall electrically neutral beam. A source utilizing a zeolite type compound, such as B-eucryptite or sodium mordenite, which on heating emits positive ions of an element in the compound, such as lithium or sodium. A source housing including precision ceramic rings with metal flanges, with substrate and grid structures carried on the flanges, with the flanges joined as by heliarc welding at their peripheries to provide a rigid mechanical and vacuum tight structure, with metal spacer rings between ceramic rings when desired.

## Claims

### Claim 1

A source for a focussed high density electrically substantially neutral beam of combined positive and negative particles, including in combination:
a housing;
a substrate mounted in said housing and having a generally spherical surface;
a plurality of strips of positive ion emitter material at said surface for emitting positive particles in beams;
a first positive ion extractor grid mounted in said housing spaced downstream from said surface;
a second positive ion accelerator grid mounted in said housing spaced downstream from said first grid;
a plurality of electron emitter strips mounted in said housing spaced downstream from said second grid; and
a third electron accelerator grid mounted in said housing between said second grid and said electron emitter strips;
with said strips of positive ion emitter material aligned between said first and second grids for defining fan shaped ion beams, and
with said third grid and electron emitter strips aligned with said first and second grids for introducing electrons with said ion beams with the electrons and positive ions mixed and traveling in a single direction at substantially the same velocity to produce substantially neutral beams adjacent said electron emitter strips and ballistically focussed to a target.

### Claim 2 (depends on 1)

A source as defined in claim 1 including:
a plurality of capacitors connected in series between said substrate and said third grid;
means connecting said first and second grids to said capacitors intermediate said substrate and third grids; and
an electrical pulse supply connected across said plurality of capacitors.

### Claim 3 (depends on 2)

A source as defined in claim 2 including means for connecting said second grid to circuit ground to provide an electric-field-free space for the positive ions moving past said grid.

### Claim 4 (depends on 3)

A source as defined in claim 3 wherein the capacitance of said capacitors and the voltage pulses of said pulse supply are of magnitudes to produce positive ions and electrons having substantially the same velocity at said third grid.

### Claim 5 (depends on 1)

A source as defined in claim 1 wherein said positive ion emitter is a compound including a loosely bound medium weight element which compound on heating emits positive ions of said element, where medium weight elements are those in the range of lithium to rubidium.

### Claim 6 (depends on 5)

A source as defined in claim 5 wherein said emitter material emits positive ions in the range of about 1000.degree. to 2000.degree. K. providing ions with random energy in the range of about 0.1 to 0.2 electron volts.

### Claim 7 (depends on 5)

A source as defined in claim 5 wherein said emitter material element is an alkali metal.

### Claim 8 (depends on 1)

A source as devined in claim 1 wherein said positive ion emitter material is B-eucryptite which on heating emits lithium ions.

### Claim 9 (depends on 1)

A source as defined in claim 1 wherein said positive ion emitter material is sodium mordenite which on heating emits sodium ions.

### Claim 10 (depends on 1)

A source as defined in claim 1 wherein said positive ion emitter material is potassium mordenite which on heating emits potassium ions.

### Claim 11 (depends on 1)

A source as defined in claim 1 wherein said first grid includes a plurality of spaced conductors, with the distance between adjacent conductors not more than substantially twice the distance between said conductors and said positive ion emitter material.

### Claim 12 (depends on 1)

A source as defined in claim 1 wherein said housing includes first and second electrical insulator support rings, with each support ring having a metal flange at each end,
with said substrate carried on a metal flange of said first support ring and said first grid carried on a metal flange of said second support ring, with adjacent metal flanges of said first and second rings joined together at their periphery.

### Claim 13 (depends on 12)

A source as defined in claim 12 including a third electrical insulator support ring with a metal flange at each end, with said second grid carried on a metal flange of said third support ring and with adjacent metal flanges of said second and third support rings joined together at their periphery.

### Claim 14 (depends on 13)

A source as defined in claim 13 including a fourth electrical insulator support ring having a metal flange at each end, with said third grid carried on a metal flange of said fourth support ring and with adjacent metal flanges of said third and fourth support rings joined together at their periphery.

### Claim 15 (depends on 12)

A source as defined in claim 12 including a metal spacer ring positioned between said first and second support rings.

### Claim 16

A source for a focussed high density electrically substantially neutral beam of combined positive and negative particles, including in combination:
a housing;
a substrate mounted in said housing and having a generally spherical surface;
means for providing positive ions over said surface;
a first positive ion extractor grid mounted in said housing spaced downstream from said surface, said first grid including a plurality of spaced conductors, with the distance between adjacent conductors not more than substantially twice the distance between said conductors and said surface;
a second positive ion accelerator grid mounted in said housing spaced downstream from said first grid;
a plurality of electron emitter strips mounted in said housing downstream from said second grid; and
a third electron accelerator grid mounted in said housing between said second grid and said electron emitter strips;
with said first and second grids defining fan shaped ion beams from said surface, and
with said third grid and electron emitter strips aligned with said first and second grids for introducing electrons with said ion beams with the electrons and positive ions mixed and traveling in a single direction at substantially the same velocity to produce substantially neutral beams adjacent said electrom emitter strips and ballistically focussed to a target.

### Claim 17 (depends on 16)

A source as defined in claim 16 wherein said housing includes first and second electrical insulator support rings, with each support ring having a metal flange at each end,
with said substrate carried on a metal flange of said first support ring and said first grid carried on a metal flange of said second support ring, with adjacent metal flanges of said first and second rings joined together at their periphery.

### Claim 18 (depends on 17)

A source as defined in claim 17 including a third electrical insulator support ring with a metal flange at each end, with said second grid carried on a metal flange of said third support ring and with adjacent metal flanges of said second and third support rings joined together at their periphery.

### Claim 19 (depends on 18)

A source as defined in claim 18 including a fourth electrical insulator support ring having a metal flange at each end, with said third grid carried on a metal flange of said fourth support ring and with adjacent metal flanges of said third and fourth support rings joined together at their periphery.

### Claim 20 (depends on 17)

A source as defined in claim 17 including a metal spacer ring positioned between said first and second support rings.

### Claim 21 (depends on 16)

A source as defined in claim 16 including:
a plurality of capacitors connected in series between said substrate and said third grid;
means connecting said first and second grids to said capacitors intermediate said substrate and third grids; and
an electrical pulse supply connected across said plurality of capacitors.

### Claim 22 (depends on 21)

A source as defined in claim 21 including means for connecting said second grid to circuit ground to provide an electric-field-free space for the positive ions moving past said grid.

### Claim 23 (depends on 22)

A source as defined in claim 22 wherein said first, second and third grids and electron emitting strips are aligned defining fan shaped beam spaces therebetween.

### Claim 24 (depends on 23)

A source as defined in claim 23 wherein the capacitance of said capacitors and the voltage pulses of said pulse supply are of magnitudes to produce positive ions and electrons having substantially the same velocity at said third grid.