Because of the good emission characteristics of oxide-coated carbon nanotube cathodes, they could be used as improved emitters in plasma environments. The most common example is the florescent lamp. Other examples are plasma displays, lasers, and space propulsion.
Operating a cathode in a plasma is more difficult than in a vacuum. When operated in a plasma, the materials of the cathode sputter away. This is the same effect we used in plasma-enhanced chemical vapor deposition to coat the nanotubes with low-work function oxides. Now the cathode is the source of material instead of the target. The cathode must be designed and operated so that its materials do not sputter away too quickly. While the nanotube cathodes are efficient emitters, they are also more fragile than a simple tungsten coil.
Testing: Plasma Discharge Simulator
To test the characteristics of various emitters in a plasma environment, we have created a plasma discharge simulator. The easiest way to describe this is as a florescent light bulb where all of the parameters (except diameter) can be controlled and measured. The temperature, pressure, plasma contents, voltage, current, length, and cathode properties can be varied.
Operating a cathode in a plasma is more difficult than in a vacuum. When operated in a plasma, the materials of the cathode sputter away. This is the same effect we used in plasma-enhanced chemical vapor deposition to coat the nanotubes with low-work function oxides. Now the cathode is the source of material instead of the target. The cathode must be designed and operated so that its materials do not sputter away too quickly. While the nanotube cathodes are efficient emitters, they are also more fragile than a simple tungsten coil.
Testing: Plasma Discharge Simulator
To test the characteristics of various emitters in a plasma environment, we have created a plasma discharge simulator. The easiest way to describe this is as a florescent light bulb where all of the parameters (except diameter) can be controlled and measured. The temperature, pressure, plasma contents, voltage, current, length, and cathode properties can be varied.