Method of forming a pellet of condensed gas and a pellet injector for injecting the same into a reactor

• US 4,904,441 A
• Filed: 09/22/1988
• Issued: 02/27/1990
• Est. Priority Date: 10/23/1987
• Status: Expired due to Fees

• Current Assignee: Forskningscenter RISO
• Original Assignee: Forskningscenter RISO
• Inventors: Sorensen, Hans, Saas, Bjarne, Weisberg, Knud V.
• Primary Examiner(s): Behrend, Harvey E.
• Application Number:
  US07/247,941
• Time in Patent Office: 523 Days
• Field of Search: 376/916, 376/101, 264/0.5, 264/28, 264/81, 425/143, 425/144, 425/160, 425/176, 425/437, 425/447
• US Class Current: 376/101
• CPC Class Codes: G21B 1/19 Targets for producing thermonuclear fusion reactions, e.g. pellets for irradiation by laser or charged particle beams
• CPC Class Codes: H05H 1/22 for injection heating G21B1/15 takes precedence
• CPC Class Codes: Y02E 30/10 Nuclear fusion reactors
• CPC Class Codes: Y10S 376/916 Methods of making fusion fuel targets

Abstract

A pellet injector for injecting pellets of condensed gas, such as hydrogen, tritium or deuterium, into a reactor comprises an arrangement of pipe guns in a cylindrical arrangement. Each pipe gun which may be made from stainless steel, has a freezing section and three axially spaced metal rings of a heat conductive metal arranged in good thermal contact with the outer surface of the pipe gun at the freezing section thereof. Each of the rings is thermally connected to a cryostat, for example by means of a copper wire. The center ring is cooled to a temperature below the condensing temperature of the gas so as to condense the gas in the freezing section of the pipe gun to form a pellet therein, and the temperature of the adjacent outer rings are maintained at temperatures exceeding the temperature of the center ring so as to obtain a pellet of a desired size. The pellets formed in the pipe guns may be expelled therefrom by a pressurized gas force pulse and injected into a reactor. The pressurized gas force pulse may be provided by using a special solenoid valve.

Claims

1. A pellet injector for injecting pellets of condensed gas into a reactor, said pellet injector comprising

a continuous length of a metal tube,

a first mass of heat conductive material arranged around a freezing section of said tube length in good thermal contact with the outer surface thereof,

second and third masses of heat conductive material arranged on either side of and closely axially spaced from said first mass and in good thermal contact with the outer surface of the tube length,

means for introducing a gas into the tube length,

cooling means for providing a temperature below the condensing temperature of said gas and being thermally connected to each of said masses so as to condense the gas within the freezing section,

means for selectively heating said masses to control the size of the pellet, and

means for pneumatically expelling a pellet formed in the freezing section from the tube length.

2. A pellet injector according to claim 1 wherein said gas introducing means are connectable to a first end of the tube length, while the pneumatic expelling means are connectable to a second end of the tube length so as to expel the pellet through said first end.

3. A pellet injector according to claim 1, wherein said masses are metal rings integrally connected to and surrounding the outer surface of the tube length.

4. A pellet injector according to claim 3, wherein said metal rings are made from pure copper.

5. A pellet injector according to claim 4, wherein said metal rings are made from annealed electrolytic copper.

6. A pellet injector according to claim 1, wherein said first, second and third masses are connected to the cooling means by first, second and third heat conductive members, respectively.

7. A pellet injector according to claim 6, wherein said heat conductive members are made from pure copper.

8. A pellet injector according to claim 7, wherein said heat conductive members are made from annealed electrolytic copper.

9. A pellet injector according to claim 6, wherein the second and third heat conductive members are somewhat less heat conductive than said first heat conductive member.

10. A pellet injector according to claim 2, wherein said pellet expelling means comprise a solenoid valve for connecting said second end of the tube length to a source of highly pressurized gas for an ultra-short period of time.

11. A pellet injector according to claim 10, wherein said solenoid valve comprises a housing defining first and second chambers therein interconnected by an interconnecting passage, a valve seat positioned at said first chamber, and a piston-like valve member unit comprising a valve member and a valve armature and being arranged in said passage so as to substantially obstruct the same and so as to be movable therein between closed and opened positions, in which the valve member is in sealing engagement with and out of engagement with the valve seat, respectively, said second chamber having a gas inlet for connecting the valve to said pressurized gas source.

12. A pellet injector according to claim 11, wherein the solenoid valve comprises a gas outlet extending axially into said first chamber and defining said valve seat at its free end, said first chamber having an annular shape and surrounding the gas outlet.

13. A pellet injector according to claim 10, wherein said freezing section is arranged adjacent to said second end of the tube length.

14. A pellet injector according to claim 13, wherein said second end of the tube length is connected to the expelling means by a connecting tube having an inner diameter exceeding that of the tube length.

15. A pellet injector according to claim 10, wherein the solenoid of the solenoid valve is connected to an electric voltage source through a switch or circuit breaker which is connected in parallel with a non-linear resistor having a resistance decreasing at increasing potential differences.

16. A pellet injector according to claim 1, wherein the tube length is made from stainless steel.

17. A pellet injector according to claim 1, wherein the wall thickness of the tube length is reduced between said masses of heat conductive material.