Plasma torches

Claim 3

In a plasma torch including a constrictor tube formed of a porous material and a means for providing a supply of working fluid to the torch to produce a plasma arc jet, the improvement comprising means for providing a supply of water to the outside of said constrictor tube and pumping means for raising the pressure of the water so supplied to a predetermined value to force the water through the walls of said porous constrictor tube into the bore thereof whereby the plasma arc column in the constrictor tube becomes further constricted and of increased energy density.

Claim 4

In a plasma torch including a constrictor tube formed of a porous material and a means for providing a supply of working fluid to the torch to produce a plasma arc jet, the improvement comprising means for providing a supply of water to the outside of said constrictor tube and pumping means for raising the pressure of the water so supplied to a predetermined value to force the water through the walls of said porous constrictor tube into the bore thereof whereby the plasma arc column in the constrictor tube becomes further constricted and of increased energy density.

Claim 5

A plasma torch as claimed in claim 2 wherein the porous material is a ceramic material.

Claim 6

A plasma torch as claimed in claim 2 wherein the pore size of the porous material lies in the range from 1.5 to 1500 microns.

Claim 7

A plasma torch as claimed in claim 4 wherein the pore size is 15 microns.

Claim 8

A plasma torch provided with a nozzle having a constrictor tube formed of a porous material, and comprising means for supplying water to the outside of the constrictor tube, pumping means for raising the pressure of the water so supplied to a predetermined value, and having a sleeve fitting coaxially around the nozzle and wherein the nozzle has a throat portion removably sealed within the sleeve and having a peripheral recess which forms, with the inside surface of the sleeve, a cavity for the flow therethrough of cooling water.

Claim 9

A plasma torch provided with a nozzle having a constrictor tube formed of a porous material, and comprising means for supplying water to the outside of the constrictor tube, pumping means for raising the pressure of the water so supplied to a predetermined value, and having a sleeve fitting coaxially around the nozzle and wherein the nozzle has a throat portion removably sealed within the sleeve and having a peripheral recess which forms, with the inside surface of the sleeve, a cavity for the flow therethrough of cooling water.

Claim 10

A plasma torch as claimed in claim 6 wherein the constrictor tube is removable, and wherein the throat portion is formed having a first part and a second part, the second part being disposed between the first part and the constrictor tube and being removeably sealed to the first part and removable from the torch, and the first part being formed with the peripheral recess and being removably sealed within the sleeve.

Claim 11

A plasma torch provided with a nozzle having a throat portion and a porous ceramic constrictor tube, and including: a sleeve fitting around the nozzle, the throat portion having an O-ring seal at each of two axially-spaced positions on the peripheral surface thereof, the O-ring seals engaging the inside surface of the sleeve, the throat portion also having a peripheral recess disposed between the O-ring seals; an inlet tube and an outlet tube communicating through the sleeve with the peripheral recess for flow and return of a coolant thereto; an annular groove in the inside surface of the sleeve disposed below the throat portion, a retaining ring fitting within the annular groove and retaining the throat portion within the sleeve; a stop within the sleeve above the throat portion for limiting the upward movement thereof, a screw cap mounted for axial movement relative to the sleeve and having a coaxial central aperture corresponding to the bore of the constrictor tube; a seal between the screw cap and the lower end of the constrictor tube; a seal between the upper end of the constrictor tube and the lower end of the throat portion; an annular cavity around the constrictor tube, a passageway communicating with said annular cavity, an inlet pipe for introducing transpiring water into the passageway, and means for controlling the pressure of water supplied to the passageway.

Claim 12

A plasma torch provided with a nozzle having a throat portion and a porous ceramic constrictor tube, and including: a sleeve fitting around the nozzle, the throat portion having an O-ring seal at each of two axially-spaced positions on the peripheral surface thereof, the O-ring seals engaging the inside surface of the sleeve, the throat portion also having a peripheral recess disposed between the O-ring seals; an inlet tube and an outlet tube communicating through the sleeve with the peripheral recess for flow and return of a coolant thereto; an annular groove in the inside surface of the sleeve disposed below the throat portion, a retaining ring fitting within the annular groove and retaining the throat portion within the sleeve; a stop within the sleeve above the throat portion for limiting the upward movement thereof, a screw cap mounted for axial movement relative to the sleeve and having a coaxial central aperture corresponding to the bore of the constrictor tube; a seal between the screw cap and the lower end of the constrictor tube; a seal between the upper end of the constrictor tube and the lower end of the throat portion; an annular cavity around the constrictor tube, a passageway communicating with said annular cavity, an inlet pipe for introducing transpiring water into the passageway, and means for controlling the pressure of water supplied to the passageway.

Claim 13

A plasma torch as claimed in claim 8 wherein the throat portion is formed having a first part and a second part, the second part being disposed between the first part and the constrictor tube and being removeably sealed to the first part, and the first part being formed with the peripheral recess and carrying the O-ring seals.