FAST-CLOSING VALVE SYSTEM FOR CYCLOTRONS

• US 3,675,072 A
• Filed: 01/28/1971
• Issued: 07/04/1972
• Est. Priority Date: 01/28/1971
• Status: Expired due to Term

• Current Assignee: James R. Tarrant, Lee D. Hunt, Richard L. Hahn, Roland L. Stone
• Original Assignee: James R. Tarrant, Lee D. Hunt, Richard L. Hahn, Roland L. Stone
• Inventors: Hahn, Richard L., Stone, Roland L., Tarrant, James R., Hunt, Lee D.
• Application Number:
  US05/110,690
• Time in Patent Office: 523 Days
• US Class Current: 315/363
• CPC Class Codes: F16K 31/02 electric F16K31/004 takes precedence; magnetic
• CPC Class Codes: H01J 13/28 Selection of substances for gas filling; Means for obtaining the desired pressure within the tube
• CPC Class Codes: H01J 2893/0086 Gas fill; Maintaining or maintaining desired pressure; Producing, introducing or replenishing gas or vapour during operation of the tube; Getters; Gas cleaning; Electrode cleaning
• CPC Class Codes: H05H 6/00 Targets for producing nuclear reactions supports for targets or objects to be irradiated G21K5/08 ; preparation of tritium C01B4/00; targets, e.g. pellets for fusion reactions by laser or charged particles beam injection H05H1/22
• CPC Class Codes: H05H 7/00 Details of devices of the types covered by groups H05H9/00, H05H11/00, H05H13/00
• CPC Class Codes: Y10T 137/7761 Electrically actuated valve

Abstract

A fast-closing valve system has been provided which operates to protect a cyclotron from loss of vacuum and backwash of radioactive contamination when using intensely alpha-active actinide targets. The valve portion consists of a valve chamber adapted for mounting in a beam tube and having aligned ports on opposite sides through which the accelerated particle beam travels. A valve gate is slidably mounted in the valve chamber between the ports and normally urged into a seated position, closing the ports, by means of compression springs. The valve gate is held open by means of an electromagnet and, when the current to the electromagnet is suddenly shorted, the magnetic field rapidly collapses and the springs slam the valve gate into the seated position. The circuit controlling the actuation of the electromagnet uses a spark plug as a pressure sensor mounted in the beam tube, downstream of the valve and when a slight pressure rise in the beam tube occurs the spark plug fires triggering the control circuit which, in turn, shorts the electromagnet. A plurality of annular baffles are mounted in the beam tube to retard the shock wave from pressurized gas backwash in the case of an accident, such as a target rupture, allowing the valve to close before the gas reaches the valve assembly.

Claims

1. In combination with a cyclotron vacuum system including at least one beam tube connected in open communication with said cyclotron vacuum system through which an accelerated particle beam from said cyclotron travels, a target chamber having a pressurized gas contained therein connected to the downstream end of said beam tube and a metal foil target window sealably disposed over an opening of said target chamber in beam receiving alignment with said beam tube, normally providing a gas-tight tight seal between said beam tube and said pressurized target chamber, a fast-closing valve system for protecting the cyclotron vacuum system from the backwash of gas from said target chamber in the event of a rupture in said target, comprising:

a valve housing positioned in said beam tube between said cyclotron and said target chamber, said housing having therein a valve chamber and aligned ports on opposite sides of an opening into said valve chamber through which said beam travels;

a valve gate slidably mounted in said valve chamber;

means for normally urging said valve gate into an extended position, closing said opening and interrupting said beam;

means including an electromagnet for holding said valve gate in a retracted position against the force of said urging means during normal operation, when said electromagnet is energized;

pressure sensing means disposed in said beam tube adjacent said target window for sensing a minute rise in pressure in said beam tube indicating a target rupture and deenergizing said electromagnet, thereby closing said valve gate; and

a plurality of baffles disposed in said line between said valve housing and said pressure sensitive means for attenuating a pressure shock wave generated by the rush of gas from a rupture in said target, thereby allowing time for said valve gate to close before said backwash of gas reaches said valve housing.

2. A fast-closing valve system as set forth in claim 1 wherein said pressure sensing means includes a spark gap device having spaced electrodes disposed in said beam tube closely adjacent to said target window well out of the path of said beam, a source of high voltage impressed across said electrodes, whereby a minute pressure rise in said line causes said spark gap to arc, shorting said electrodes, an adjustable current source connected to said electromagnet for supplying energizing current to said electromagnet, and switching means for sensing the arcing of said spark gap and shorting said electromagnet, thereby closing said valve gate.

3. A fast-closing valve system as set forth in claim 2 wherein said beam tube is circular in cross section and said plurality of baffles includes a first plurality of annular rings positioned adjacent said target window in a predetermined spaced apart relationship and having aligned central openings disposed for free passage of said beam therethrough and a second plurality of annular rings positioned adjacent the downstream opening of said valve housing in the same said predetermined spaced apart relationship and having aligned central openings disposed for free passage of said beam therethrough.

4. A fast-closing valve system as set forth in claim 3 wherein said first and second pluralities of baffles are equally spaced apart by distances of approximately 1 to 3 beam tube diameters.