Plasma jet generating apparatus with plasma confining vortex generator

• US 4,620,080 A
• Filed: 06/25/1985
• Issued: 10/28/1986
• Est. Priority Date: 06/27/1984
• Status: Expired due to Fees

• Current Assignee: Nippon Steel Corporation
• Original Assignee: Nippon Steel Corporation
• Inventors: Kobayashi, Akira, Arata, Yoshiaki
• Primary Examiner(s): PASCHALL, MARK H
• Application Number:
  US06/748,421
• Time in Patent Office: 490 Days
• Field of Search: 219/121 PM, 219/121 PP, 219/121 PQ, 219/121 PN, 219/121 P, 219/74, 219/75, 313/231.31-231.51
• US Class Current: 219/121.5
• CPC Class Codes: H05H 1/3405 Arrangements for stabilising or constricting the arc, e.g. by an additional gas flow
• CPC Class Codes: H05H 1/3452 Supplementary electrodes between cathode and anode, e.g. cascade
• CPC Class Codes: H05H 1/3468 Vortex generators

Abstract

A plasma jet generating apparatus including a torch center electrode, a torch nozzle, a first DC source, and a vortex flow/discharge unit. The unit includes a second DC power source, a gas diverter nozzle, and a vortex flow chamber. The second DC power source is used to create a high temperature and high power plasma jet. The vortex flow chamber, together with the gas diverter nozzle, is used to apply a thermal pinch effect to the plasma jet to be output from the gas diverter nozzle.

Claims

1. A plasma jet generating apparatus comprising:

a torch center electrode;

a torch nozzle having first and second ends and into the first end of which said torch center electrode is directed;

a first DC power source connected across the first and the second ends of said torch nozzle for producing a plasma jet in cooperation with a working gas caused to flow through said torch nozzle; and

a vortex flow/discharge unit connected to said second end of said torch nozzle, said unit comprising;

a second DC power source, one end of which is connected to said torch nozzle;

a gas diverter nozzle spaced from the second end of said torch nozzle and to which the other end of said second DC power source is connected; and

a vortex flow chamber connected between said gas diverter nozzle and said torch nozzle, said chamber having a cylindrical shape defined by a cylindrical wall, said cylindrical wall having a plurality of sets of at least four through holes extending therethrough tangentially to the inside cylindrical surface of said cylindrical wall, the through holes of each set being spaced around the periphery of said cylindrical wall and the holes in each set being aligned with corresponding holes in the other sets along lines on the cylindrical wall which are parallel to the cylindrical axis of said chamber, said chamber having a donut-shaped end wall perpendicular to the cylindrical wall and on the end remote from said torch nozzle, said end wall being constituted by the end wall of said gas diverter nozzle which is toward said torch nozzle; and

means for directing a working gas under pressure through said through holes into said vortex flow chamber for forming a vortex gas tunnel of the working gas enclosing the plasma jet therein, whereby the plasma jet is subjected to a thermal pinch effect through the gas tunnel and the plasma jet is produced while maintaining thermal isolation of the plasma jet from the inside wall of the gas diverter nozzle.

2. A plasma jet generating apparatus as claimed in claim 1 in which said working gas directing means comprises means for supplying said working gas into said through holes at a velocity of at least 100 m/sec.

3. A plasma jet generating apparatus as claimed in claim 2 in which said working gas directing means comprises means for supplying said working gas into said through holes at a flow rate of at least 200 l/min.

4. A plasma jet generating apparatus as claimed in claim 1 in which said gas diverter nozzle has a passage therein around the nozzle for accommodating a cooling medium therein.

5. A plasma jet generating apparatus as claimed in claim 1 further comprising at least one further vortex flow/discharge unit connected in series along the direction of the plasma jet, said further vortex flow/discharge unit having the same construction as said first mentioned vortex flow/discharge unit.

6. A plasma jet generating apparatus as claimed in claim 5 in which said second DC power sources of each of said vortex flow/discharge units are connected across said units with the same polarity.

7. A plasma jet generating apparatus as claimed in claim 5 in which said second DC power sources of adjacent vortex flow/discharge units are connected across the units with opposite polarity.I