Gas laser with at least one excitation tube wherethrough gas is actually flowing

Abstract

A method of lasing gas, a fast axial flow gas laser and an excitation tube for a fast axial flow gas laser are disclosed. Increased thermal energy per mass flow unit of the gas flowing through the excitation tube of the laser can be applied to the gas by controlling at least along a part of the tube the extent of a central area of higher speed gas flow which is surrounded by a circumferential low speed, speed dependent boundary layer by steadily varying the cross-section area of the excitation tube at least along the part thereof to compensate for the circumferential low speed boundary layer.

I claim: 
     
       1. In an axial flow gas transport laser comprising an excitation tube .Iadd.with an internal surface .Iaddend.through which gas flows along an axis of said tube, an inlet arrangement .Iadd.located at one end of said excitation tube .Iaddend.to feed gas towards said excitation tube, and an outlet arrangement .Iadd.located at the other end of the excitation tube .Iaddend.to discharge gas from said excitation tube .Iadd.whereby the gas fed to said excitation tube flows along the axis of the tube over the entire length of the tube between the inlet arrangement and the outlet arrangement.Iaddend., the improvement comprising at least one of said inlet and outlet arrangements comprising a circumferential opening arrangement evenly distributed along the periphery of said excitation tube, .[.substantially.]. in a cross-section plane of said tube, and a gas flow channel arrangement .Iadd.with internal channel surfaces leading .Iaddend.to said opening arrangement, said gas flow channel arrangement at said opening arrangement being directed at least .[.substantially.]. .Iadd.predominately .Iaddend.in the direction of the excitation tube axis .[.and into the excitation tube.]. .Iadd., an internal channel surface of said gas flow channel arrangement steadily transmitting into said internal surface of said tube along a portion of said opening arrangement .Iaddend.for preventing wide .[.serial.]. .Iadd.areal .Iaddend.turbulances of the flowing gas in said excitation tube. 
     
     
       2. The laser according to claim 1, wherein the axes of said gas flow channel arrangement at said opening arrangement define a symmetrical cone around said axis of said excitation tube. 
     
     
       3. The laser according to claim 1, wherein said opening arrangement comprises a ring gap. 
     
     
       4. The laser according to claim 1, wherein said flow channel arrangement communicates with an equalizing chamber, said equalizing chamber being connected with one of a gas feed arrangement and a gas discharge arrangement. 
     
     
       5. The laser according to claim 4, wherein said equalizing chamber comprises an annular chamber around said axis of said excitation tube. 
     
     
       6. The laser according to claim 1, wherein said opening arrangement being at least in part defined by at least parts of an electrode arrangement for electrically exciting said gas within said excitation tube. 
     
     
       7. The laser according to claim 1, wherein said opening arrangement comprises at least two circumferential opening rings disposed in spaced relationship at the circumference of said excitation tube. 
     
     
       8. The laser according to claim 1, wherein said outlet arrangement comprises at least one bucket ring arranged along the circumference of said excitation tube. 
     
     
       9. The laser according to claim 1, wehrein said outlet arrangement comprises a pressure gas pipe and a gas discharge pipe, the opening of said pressure gas pipe being disposed opposite an opening of said gas discharge pipe and the axis of said pressure gas pipe being substantially aligned with the axis of said discharge gas pipe so as to improve gas discharge through said gas discharge pipe by pressurized gas entrained discharge. 
     
     
       10. The laser according to claim 1, wherein at least a part of said excitation tube has an inner cross-section departing from circular form. 
     
     
       11. The laser according to claim 1, further comprising an electrode arrangement to excite said gas within said excitation tube, said electrode arrangement comprising at least one electrode disposed along the circumference of the inner wall of said excitation tube, substantially without forming at least one of a circumferential stop and a circumferential groove at said inner wall. 
     
     
       12. The laser according to claim 11, wherein said electrode forming an even link from one part of said excitation tube of a first inner diameter to a second part thereof of a second inner diameter disposed coaxially to said one part. 
     
     
       13. The laser according to claim 1, further comprising an electrode arrangement at said excitation tube for electrically exciting said gas within said excitation tube and electrical control means connected to said electrode arrangement for controlling the electrical field pattern within and along said excitation tube. 
     
     
       14. The laser according to claim 13, wherein said electrode arrangement comprises at least one electrode formed by several sub-electrodes separately disposed around said axis of said excitation tube, said electrical control means comprising a control unit, connected to said sub-electrodes for electrically feeding said sub-electrodes in a predetermined time sequence. 
     
     
       15. The laser according to claim 1, wherein said inlet arrangement comprises a gas-feed-pipe arrangement with dividing means, sub-dividing the inner cross-section of said gas-feed-pipe arrangement into a multitude of separate flow paths. 
     
     
       16. The laser according to claim 15, wherein said dividing means comprises at least one grid arranged within said gas-feed-pipe arrangement. 
     
     
       17. The laser according to claim 15, wherein said dividing means comprising a multitude of sub-dividing walls. 
     
     
       18. The laser according to claim 17, wherein said walls are arranged in the form of a honey comb pattern. 
     
     
       19. The laser according to claim 1, wherein said inlet arrangement comprises a gas-feed-pipe arrangement, said gas-feed-pipe arrangement comprising a steady diminishment of its inner cross-section followed by a steady re-enlargement of its inner cross-section.