# US 4,394,579 A · Laser induced plasma production for isotope separation

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- Number: US 4,394,579 A
- Document ID: US4394579A
- Status: Granted
- Kind: A
- Application number: 06/086,982
- Filed: 1979-10-22
- Granted: 1983-07-19
- Earliest claimed: 1979-10-22
- Inventors: Fred R. Schwirzke
- Web page: https://patentgrep.com/patent/US4394579A

## CPC

- B01D 59/34: Separation by photochemical methods
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)

## Abstract

In a system for isotope enrichment, a method and apparatus for separating atoms of one isotope type from an environment containing plural isotope types. Tunable lasers or laser systems are used to selectively pump atoms of the desired isotope to a metastable excited state several eV above the isotope atom ground state. A reduced ionization energy is then supplied to atoms of the metastable isotopes taking advantage of the longer lifetimes achieved. The resulting plasma created by ionizing atoms of the isotope in the metastable state is subjected to electromagnetic fields to separate atoms of the desired isotope.

## Claims

### Claim 1

The method of separating selected atoms which absorb radiation of one frequency from other atoms which absorb radiation of different frequencies comprising:
(a) heating a mass of material containing both types of said atoms until a vapor of said material is formed;
(b) irradiating said vapor with a laser source operating at said one frequency whereby said selected atoms are pumped into excited metastable states above the ground state of said selected atoms;
(c) supplying a continuous source of thermal energy to said selected atoms in said excited metastable states forming an ionized plasma of said selected atoms; and
(d) separating said ionized plasma from all said other atoms.

### Claim 2 (depends on 1)

The method of claim 1 wherein said laser source is a pulsed laser.

### Claim 3 (depends on 1)

The method of claim 1 wherein said laser source is a continuous laser.

### Claim 4 (depends on 1)

The method of claim 1 wherein said continuous source of thermal energy is a heating grid.

### Claim 5 (depends on 1)

The method of claim 1 wherein said continuous source of thermal energy is a heated neutral gas.

### Claim 6 (depends on 1)

The method of claim 1 wherein said continuous source of thermal energy is an electron beam.

### Claim 7 (depends on 1)

The method of claim 1 wherein said continuous source of thermal energy is a hot metal surface.

### Claim 8 (depends on 1)

The method of claim 1 wherein said separating includes applying external electromagnetic forces to said ionized plasma.

### Claim 9

Apparatus for separating selected atoms which absorb radiation of one frequency from other atoms which absorb radiation of different frequencies comprising:
(a) a housing;
(b) an oven having an outlet to said housing for heating a mass of material containing both types of said atoms until a vapor of said material is formed;
(c) means for directing said vapor into said housing connected between said oven and said housing;
(d) means for pumping said selected atoms in said vapor into excited metastable states above the ground state of said selected atoms;
(e) means for continuously ionizing said selected atoms in said excited states by a continuous thermal energy source whereby an ionized plasma of said selected atoms is formed; and
(f) means for separating said ionized plasma of said selected atoms from said other atoms.

### Claim 10 (depends on 9)

The apparatus of claim 9 wherein said housing includes a vacuum vessel.

### Claim 11 (depends on 9)

The apparatus of claim 9 wherein said exciting means is a tunable continuous laser.

### Claim 12 (depends on 9)

The apparatus of claim 9 wherein said exciting means is a tunable pulsed laser.

### Claim 13 (depends on 9)

The apparatus of claim 9 wherein said ionizing means is a heating grid.

### Claim 14 (depends on 9)

The apparatus of claim 9 wherein said ionizing means is a heated neutral gas.

### Claim 15 (depends on 9)

The apparatus of claim 9 wherein said ionizing means is an electron beam.

### Claim 16 (depends on 9)

The apparatus of claim 9 wherein said ionizing means is a hot metal surface.

### Claim 17 (depends on 9)

The apparatus of claim 9 wherein said separating means is an externally applied electromagnetic field.