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Los Alamos National Laboratory developed the Atmospheric Pressure Plasma Jet (APPJ®) technology at a cost of millions of dollars. Today, APJeT, Inc. holds exclusive license to this novel technology, and the technology's inventors lead the development efforts at our facility in Santa Fe, New Mexico. In addition, APJeT has formed a strategic partnership with Air Products & Chemicals, Inc. (APCI) and has sublicensed the technology to them for specific applications. Air Products maintains an active APPJ development effort at its Allentown, Pennsylvania, headquarters and also offers helium recycling, which can make APJeT technology more economical in many applications.
The APJeT technology is a unique tool with many applications.
How It Works
The original invention was known as the Round Jet. The APPJ Round Jet produces a plume similar to a conventional Bunsen burner flame, it can maintain this "cold flame" at a temperature that is lower than the exhaust of a hair dryer. Unlike a plasma torch, with a temperature of several thousand degrees, the APPJ can be maintained at temperatures from 50° C to 300° C. The APPJ's temperature is a function of gas flow, radio frequency (RF) power and external cooling.
High Efficiency
The APPJ generates a non-thermal, stable, homogeneous discharge that is up to 1,000 times more efficient for producing active chemical species than are older and conventional atmospheric pressure plasmas such as corona or dielectric barrier discharges (DBDs). The APPJ is also more efficient than the various atmospheric pressure glow discharges (APGD) that run helium carrier gas in DBD-like devices at audio frequencies.
Design Avoids Arcing
APPJ uses RF electric fields, at 13.56 MHz to 60 MHz, to produce a unique, non-thermal, glow-discharge plasma that operates at atmospheric pressure and at power densities up to 500 W/cm3. Using RF excitation, together with a helium carrier gas and a patented electrode geometry, the technology avoids arcing. In contrast, most conventional atmospheric pressure plasmas use dielectric covers over the electrodes to quench arcing.
Along with the helium carrier, the jet is fed a small percentage of a reactive gas, which becomes dissociated to produce the active, short-lived species needed for materials processing applications. The dissociation occurs when the gas is passed through the plasma, due to collisions with energetic electrons present in the plasma. Once the gas exits the plasma volume, the ions and electrons rapidly recombine, leaving only the longer-lived reactive neutrals, including atoms and radicals (e.g., O, H, OH, N), as well as metastable species (e.g., O2* and He*).
Technology Supports Downstream and In-Situ Modes
The APPJ technology licensed to APJeT allows both downstream and in-situ methods of treatment.
In the downstream (or remote) mode, the reactive chemical species are directed downstream at high velocity to carry thin films onto the work surface. This makes it possible to treat complex shapes. It also makes it possible to feed precursors into the afterglow region to minimize monomer fragmentation and to eliminate chamber/electrode coating-the major cause of downtime in manufacturing applications using competing methods. APJeT's unique deposition technology enables the use of plasmas for surface treatment as well as thin film deposition of planar or 3-D geometries. It is also conducive to the use of unique gas-phase chemistries, because the precursor gas is never exposed to the energetic environment of the plasma. Instead, the precursor gas works purely through chemical reactions.
Alternatively, the substrate can be placed directly inside the plasma discharge for an in-situ treatment. This greatly reduces consumption of feed gas and power, and minimizes footprint requirements for the equipment. The APPJ technology licensed to APJeT uses both methods.
Advantageous for Many Applications
Using a parallel plate geometry, such as the Flat Jet, rather than the cylindrical Round Jet configuration makes the APPJ technology easily scalable for treatment of large-area substrates. The combination of fast processing rates, atmospheric pressure operation, and easy scalability of the plasma system makes this technology highly valuable for a host of material processing opportunities.
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