Gas discharge structure for an R.F. excited gas laser

• US 4,817,108 A
• Filed: 03/17/1988
• Issued: 03/28/1989
• Est. Priority Date: 03/17/1987
• Status: Expired due to Fees

• Current Assignee: Coherent Inc (Coherent Corp.)
• Original Assignee: Coherent Inc (Coherent Corp.)
• Inventors: Allcock, Geoffrey
• Primary Examiner(s): Scott, Jr., Leon
• Application Number:
  US07/169,289
• Time in Patent Office: 376 Days
• Field of Search: 372/35, 372/61, 372/64, 372/82, 372/87, 372/88, 372/55, 372/83
• US Class Current: 372/82
• CPC Class Codes: H01S 3/041 for gas lasers H01S3/0401 takes precedence
• CPC Class Codes: H01S 3/0975 using inductive or capacitive excitation

Abstract

A gas discharge structure for an R.F. discharge excited gas laser comprising an R.F. electrode (1), a ground electrode (2) and a metal coolant carrying pipe (4) carried bie said R.F. electrode. The pipe (4) is connected at each end to coolant source or drain at ground potential. The coolant carrying pipe (4) is inductively decoupled at each end from ground potential and has a wall thickness many times greater than the "R.F. skin depth" at the R.F. frequency of operation.

Claims

1. A gas discharge structure for an R.F. discharge excited gas laser comprising:

an R.F. electrode;

a ground electrode; and

means for cooling said R.F. electrode, said means including a metal coolant carrying pipe the ends of which are connectable to a coolant source at ground potential, with the sections of the pipe between a center section and the ends having sufficient inductance at the R.F. frequency of operation to decouple each end from ground potential.

2. A gas discharge structure for an R. F. discharge excited gas laser as recited in claim 1 wherein said metal coolant carrying pipe has a wall thickness many times greater than the R.F. skin depth at the R.F. frequency of operation.

3. A gas discharge structure for an R.F. discharge excited gas laser according to claim 1 wherein said inductive sections of the pipe are coiled to increase the inductance thereof.

4. A gas discharge structure for an R.F. discharge excited gas laser according to claims 1 or 3 wherein a capacitor is connected in parallel with each inductive section of the pipe and is tuned to parallel resonance with the inductive section at the R.F. frequency of operation.

5. A gas discharge structure for an R.F. discharge excited gas laser according to claim 1 wherein said coolant carrying pipe is secured to the surface of the R.F. electrode, in thermal contact therewith.

6. A gas discharge structure for an R.F. discharge excited gas laser according to claim 1 wherein the radially outer portion of said center section of the coolant carrying pipe defines the R.F. electrode.

7. A gas discharge structure for an R.F. discharge excited gas laser comprising:

a tubular outer ground electrode;

a radially inner metal coolant carrying pipe the ends of which are connected to and supported by the ground electrode, and wherein the radially outer portion of the center section of said coolant carrying pipe defines an R.F. electrode, and with the sections of the pipe between the center section and the ends having sufficient inductance at the R.F. frequency of operation to decouple each end from ground potential.

8. A gas discharge structure for an R.F. discharge excited gas laser according to claim 7 wherein the tubular ground electrode and the metal coolant carrying pipe define an annular discharge region therebetween.

9. A gas discharge structure for an R. F. discharge excited gas laser as recited in claim 7 wherein said coolant carrying pipe has a wall thickness many times greater than the R.F. skin depth at the R.F. frequency of operation.

10. A gas discharge structure for an R.F. discharge excited gas laser according to claim 7 wherein said inductive sections of the pipe are coiled to increase the inductance thereof.

11. A gas discharge structure for an R.F. discharge excited gas laser according to claims 7 or 10 wherein a capacitor is connected in parallel with each inductive section of the pipe and is tuned to parallel resonance with he inductive section at the R.F. frequency of operation.

12. A gas discharge structure for an R.F. discharge excited gas laser according to claims 7 wherein said coolant carrying pipe is coaxially aligned within said outer tubular ground electrode.

13. A gas discharge structure for an R.F. discharge excited gas laser comprising:

a hollow metal tube having a first surface defining an R.F. electrode and a second surface, opposite the first, defining a ground electrode and wherein the side walls of the tube separating the first and second surfaces thereof are inductive and have a high impedance at the R.F. frequency of operation thereby decoupling the R.F. electrode from the ground electrode.

14. A gas discharge structure for an R.F. discharge excited gas laser according to claim 13 wherein slots are formed in the side walls of the hollow metal tube to increase the inductance thereof.

15. A gas discharge structure for an R.F. discharge excited gas laser according to claims 13 or 14 wherein external capacitors are connected in parallel with the inductive side walls of the tube in order to form a parallel resonant circuit at the R.F. frequency of operation.

16. A gas discharge structure for an R.F. discharge excited gas laser according to claim 13 wherein the hollow metal tube is of rectangular section.