Practical Excersises

Advanced Practical Excersise

Microplasmas (401)

In this experiment a micro-atmospheric pressure plasma jet is examined and applied for simple surface modifications. Such modifications, e.g. In the wettability are made possible by the admixture of molecular components such as, for example, oxygen, which are dissociated in the plasma. Within the scope of this experiment the atomic oxygen density is to be determined by means of optical emission spectroscopy (actinometry) and correlations with resulting surface properties of samples (contact angle measurements) are to be investigated. The experiment thus provides a comprehensive overview of the physics and application of atmospheric pressure plasmas and is located at the interface between plasma physics, plasma diagnostics and surface physics.

This experiment is now available online

Contact:

Dr. Volker Schulz-von der Gathen / Patrick Preissing

 

 

Advanced practical excersiSe

Determination of excitation temperatures

A hydrogen plasma is selectively changed. It burns between two water-cooled, cone-shaped copper electrodes of variable distance at variable pressure and current. Its form of existence ranges from the non-thermal region to the transition region to the partial-local thermal region, from the current normal to the high-current contracted glow discharge. The plasma state in these different regions is determined spectroscopically by examination of the Balmer lines and characterized by means of excitation temperatures.

Contact:

Dr. Volker Schulz-von der Gathen / Dr. Katharina Grosse

 

Advanced practical excersise

Mass spectrometry in reactive plasmas

Reactive plasmas are an important tool for many modern applications, for example in the automotive or semiconductor industry. Plasma coatings provide workpieces with new properties such as special hardness or prevent the permeation of gases or liquids by plastics. Plasma etching makes it possible to etch nanometers large structures in silicon. The central question in the investigation of reactive plasmas is the search for the dominant species, which lead to a coating or to etching. In a plasma, a starting gas is dissociated and ionized, and the resulting particles interact with the surface. A variety of species can simultaneously contribute to material synthesis or erosion. However, the isolation of individual mechanisms against the background of a very complex plasma chemistry is not readily possible.

Mass spectrometry is a very suitable diagnostic tool, since it is sensitive to a variety of different species. This will be discussed in the present practical experiment. An inductive methane discharge is selected as an example. After learning the handling of the mass spectrometer and analyzing the signals of some neutral source gases, the composition of a plasma is to be investigated as a function of the process parameters. In addition, the so-called threshold spectroscopy is to be carried out, in which selective radicals in a plasma can be detected.

Contact:

Dr. Wolfgang Breilmann