Plasma is the ‘hidden champion’ of industrial innovation – Prof. Christian Oehr
When asked what a plasma is, Prof. Oehr explained that Plasma is created when an electric spark excites gas to produce free electrons and ions. This mix of ions, electrons and gas molecules can become a plasma if the charged density is large enough.
Why are plasma so useful, the electron bombardment that excites gas molecules together with ions, electronically excited molecules and radicals, will bombard any material that you bring into contact with the plasma. This energy applied to the material’s surface can modify its chemistry or purify a material surface by destroying undesired organic contaminants.
What are the current uses of plasma? Plasma are used for a wide range of applications such as etching silicon, depositing insulators and metal conductors in the manufacture of semiconductors. Light sources such neon tubes contain plasma and he says that plasma technologies started more than 100 years ago with lamps(Phillips). However, Prof. Oehr, missed a major plasma application, in 1857 when Siemens proposed a novel type of electrical gas discharge that could generate ozone from atmospheric pressure oxygen or air. Plasma applications have in fact been part of industry for over 150 years.
“The main application of plasma today is surface treatment — you can deposit different minuscule nano-structures on materials to change their properties, for example, modifying plastics so that they will bond with each other, or to coat metals to minimize corrosion or scratching. Almost every kind of industry has an application for plasma, it’s a hidden champion.’ Explains Prof. Oehr. In a way we are used to thinking about the cost of a material being based whole material where it is usually only the surface that matters in many applications. Therefore making an expensive surface on a cheap material is a very efficient way on increasing the value of products. An area where German industry have been leaders.
Prof. Oehr explains his own interests in water treatment.
‘So here you have water passing through in a thin film, which is in contact with a plasma and will be treated by reactive species out of the discharge, destroying toxic contaminants in the water and purifying it. With the unit we developed, this works well but the throughput is not so high — up to 250 litres per hour. So at this point, it would be suited only to special situations with limited volume, like purifying hospital wastewater which contains medication contaminants that cannot be destroyed with normal wastewater treatment.’
The article goes on the explain Prof. Oehr’s own research interests and exciting areas in plasma research.