Tekna

INDUCTION PLASMA TORCH

RF plasma or Induction plasma is commonly known as radio frequency (RF) or high frequency (HF) discharges. Plasmas are generated through the electromagnetic coupling of electrical energy into a discharge cavity. Induction plasma technology has been studied for more than 50 years and was used in the early seventies for re-entry studies by NASA and other space agencies. Over the past 30 years the technological use of induction plasma torches for a wide range of applications has been the subject of intense studies and numerous scientific publications.

Tekna's induction plasma torch is based on a patent-protected technology developed in the eighties. They feature:

the use of a proprietary ceramic plasma confinement tube
an advanced aerodynamic gas sheathing design
high velocity film cooling of the plasma confinement tube
operation under a wide range of conditions with oxidizing, reducing and inert plasma gases
a high-purity process, since the plasma is not in contact with any electrodes
large-volume discharge which allows for a long contact time between the materials to be processed and the plasma.

Since its foundation in 1990, Tekna has developed a complete line of induction plasma torches, which is capable of operation with power ratings ranging from tens to hundreds of kW.

Torch Model	RF Generator Power (kW)
PL-35	30
PS-50	60
PS-70	100
PS-100	200

A plasma jet generated in an induction plasma torch gives a high-temperature environment (5000 to 10 000 K) with a high specific enthalpy (1-10 MJ/kg, depending on the plasma gas composition). The central axial injection mode makes the handling of the precursor feeding into the discharge much easier. Because the residence time is longer than on DC plasmas, the precursor can be better treated and particles are heated thoroughly. For this reason, Tekna has developed a number of water-cooled probes, which are shown in a photo on this page. They are well adapted for different Tekna torches and material injection needs.

Torch Nozzle

Tekna induction plasma torches are also characterized by their ability to use interchangeable plasma jet exit nozzles depending on process needs. Divergent nozzles are recommended for powder spheroidization applications while convergent nozzles are best adapted to plasma deposition and coating applications. Tekna’s supersonic nozzles offer a unique capability for the deposition of nano materials and nanostructured coating. The combination of the supersonic nozzles and the central powder axial injection capability of the Tekna torches allows for the heating and melting of the individual powder particles (or precursor) in the high pressure region of the discharge while accelerating the molten droplets towards the substrate in the low pressure region of the discharge. A photograph of the front end of a Tekna torch with a Mach 1.5 nozzle attachment is shown together with pictures of the plasma jet obtained in this case with different plasma gas compositions.

[Convergent nozzle] [Divergent nozzle] [Supersonic nozzle]

PS-50 induction plasma torch with supersonic (Mach 1.5) nozzle attachment (left)
and photographs of the generated plasma jets with different plasma gas compositions

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