GB2202079A

GB2202079A - Improvements in or relating to gas lasers

Info

Publication number: GB2202079A
Application number: GB08118256A
Authority: GB
Inventors: Harvey Nicholas Rutt
Original assignee: UK Atomic Energy Authority
Current assignee: UK Atomic Energy Authority
Priority date: 1980-06-23
Filing date: 1981-06-17
Publication date: 1988-09-14
Also published as: GB2202079B

Abstract

A gas laser for use in the separation of uranium isotopes in which the lasing medium includes a monohaloacetylene.

Description

Improvements in or relating to gas lasers The present inventionrelates to gas lasers, and more particularly to a gas laser for use in a laser isotope separation process.

Laser isotope separation is a term which is used to describe processes by means of which a particular isotope, or isotopes, of an element can be separated from other isotopes of the element.

In general a gaseous mixture which includes an isotope of interest is illuminated by a laser the frequency of which is preferentially absorbed by a constituent of the gaseous mixture which includes the said isotope and excites that constituent only in some way. The excited constituent is then removed by means of a property which it possesses and which the unexcited constituents of the gaseous mixture do not possess.

For example the excited constituent may be ionised or made chemically more reactive than the constituents of the gaseous mixture which have not been ionised.

An isotope of particular interest is the 235 isotope of uranium which is required for the generation of nuclear power and which occurs as only O.7t of naturally occurring uranium. In principle laser isotope separation can be carried out using the gaseous compound UF6. However, due to the complicated absorption spectrum and small isotopic shift of uranium and its compounds, the development of a practicable process is critically dependent upon the invention of a satisfactory laser, and so far this does not seem to have been achieved.

According to the present invention there is provided a gas laser the lasing medium of which includes a monohaloacetylene.

Any of the isotopes of carbon or the halogens can be used. Also the remaining hydrogen atoms in the mono haloacetylene can be replaced by deuterium.

The invention will now be described, by way of example, with reference to the accompanying drawing, which is a diagrammatic representation of a laser embodying the invention.

Referring to the drawing, a gas laser for use in a process for separating 235U from 238U in a gaseous form consists of a tube 1 some 2.5 metres long and 10 cm in diameter which is closed by two optically flat glass plates 2 made of potassium bromide or chloride. The plates 2 are positioned at Brewster's angle with reference to polarised light produced in the enclosed tube 1. The tube 1 is surrounded by a cooling jacket 3. An optical cavity is formed by a concave mirror 4 and a partially reflecting plane mirror 5. The mirror 4 has a radius of curvature of 20 metres and is gold-plated. A blazed diffraction grating-6 having one hundred lines per inch is so positioned that radiation from a carbon dioxide pumping laser 7 can be caused to pass through a lasing medium contained in the tube 1, while the laser radiation from the tube 1 is reflected to and from the mirror 5.

The lasing medium within the tube 1 is monofluoroacetylene (HCCF) at a pressure of about 0.5 Torr, and a temperature of about -11OOC although other temperatures can be used. In fact the lowest temperature is determined solely by the need to maintain a pressure of about 0.5 Torr in the tube 1. The highest usable temperature has not yet been determined, but ii certainly is higher than 25 0C.

Either the fundamental w3 or the combination V4 + w5 band of the HCCF molecule can be stimulated by the laser 7.

The #3 band can be stimulated by utilising the P(6), P(12), P(14), P(18), R(10), R(12) or R(20) transitions of the 12C16O2 molecule. The #4 + #5 band can be stimulated by utilising the Pc14), P(28), R(6), R(16), R(18) or R(24) transitions of the 12C6O2 molecule. The HCCF molecule then produces laser radiation at various wavelengths in the range 16.4 to 18 . Of the pump lines mentioned above, the P(14) line is not available at room temperature.

Also by utilising the P(12), P(18), R(10), R(12) or R(2O) lines of the 12C1602 molecule, one can produce 2 laser radiation in the region of 20 - 21 p, and possibly in the range 14 - 15 . This radiation comes from the following transitions: Pump Band Lasing Band fundamental #3 -difference #3 - #4 #3 - #5 #4 - #5 combination #4 + #5 fundamental #4 The analogous compound DCCF behaves in the same way.

Another preferred monohaloacetylene is monochloro acetylene (HCCCl). This compound should be used at temperatures in the region of -110 C and again at pressures of about 0.5 Torr. Either the P(28) or P(36) lines of the 12C1602 molecule will produce lasing action from the #4 + #5 combination band of the HCCC1 molecule at a wavelength near 16 p.

Other monohaloacetylenes which can be used are tabulated below, together with the appropriate bands which can be excited to produce lasing action.

Compound Band #3 DCC1 #3 + #5 or 2 #4 HCCBr #4 + #5 or #3 + #5 DCCBr #3 + #4 or #3 + #5 Also, any stable or long half life isotopes on carbon or the halogens can be used to form the monohaloacetylene.

Claims

Clains

1. A gas laser the lasing me-liu;l of which includes a monohaloacetylene.

2. A laser according to Claim 1, wherein the monohaloacetylene is monofluoroacetylene.

3. A laser according to Claim 2, wherein the monofluoroacetylene is at a pressure of about 0.5 Torr.

4. A laser according to Claim 3, wherein the monofluoroacetylene is at a temperature of between -110 and 250C.

5. A laser according to any of Claims 2 to 4, wherein the fundamental V3 band of the monofluoroacetylene molecule is stimulated by laser radiation derived from the following transitions of the 12C16O2 molecule, P(6), P(12), 2 P(14), P(18), RclO), R(12) or Rc20).

6. A laser according to any of Claims 2 to 4, wherein the combination #4 + #5 band of the monofluoroacetylene molecule is stimulated by laser radiation derived from the following transitions of the 12C16Q2 molecule, P(14), P(28), R(, RCl6), R(18) or R(24).

7. A laser according to Claim 1, wherein the monohaloacetylene is monochloroacetylene.

8. A laser according to Claim 7, wherein the monochloroacetylene is at a pressure of about 0.5 Torr and a temperature of about -110 C.

9. A laser according to Claim 8, wherein the w4 ±95 combination band of the monochloracetylene molecule is stimulated by means of laser radiation derived from the

9. A laser according to Claim 8, wherein the V4 + combination band of the monochloroacetylene molecule is stimulated by means of laser radiation derived from the P(28) or P(36) transition of the 12C1602 molecule.

2

10. A laser substantially as hereinbefore described and with reference to the accompanying drawing.

Amendments to the claims have been filed as follows Claims 1. A gas laser the lasing medium of which includes a monohaloacetylene as the active lasing constituent of the lasing medium.

2. A laser according to Claim 1, wherein the monohaloacetylene is monofluoracetylene.

5. A laser according to any of Claims 2 to 4, wherein the fundamental V3 band of the monofluoracetylene molecule is stimulated by laser radiation derived from the following transitions of the 12C1602 molecule, P(6), P(12), P(14), P(18), R(10), R(12) or R(20).

6. A laser according to any of Claims 2 to 4, wherein the combination 94 + w5 band of the monofluoroacetylene molecule is stimulated by laser radiation derived from the following transitions of the 12C1602 molecule, P(14), P(28), R(6), R(16), R(18) or R(24).

7. A laser according to Claim 1, wherein the monohaloacetylene is monochloroacetyelne.

8. A laser according to Claim 7, wherein the monochloroacetylene is at a pressure of about 0.5 Torr and a temperature of about -1100C.