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The seminar is given at a tutorial level for the general audience, and contains several interesting photos (and also movies)
of glowing structures called 'fireballs' , and exiting phenomena which can be observed in laboratory plasmas.
http://www.phys.uit.no/~ashild/plasmalab/HvaErPlasma/indexl.htm
Abstract:
Double layers are nonlinear potential structures consisting of two adjacent layers of positive and negative charges, in which the existing potential jump creates an electric field. One common way to obtain a double layer is to positively bias an electrode immersed in an equilibrium plasma. In this case, a complex space charge structure in form of a quasi-spherical intense luminous body attached to the electrode is obtained which we call "fireball".
Experimental investigations showed that such a complex space charge structure consists of a positive “nucleus” (an ion-rich plasma) surrounded by a nearly spherical double layer. The potential drop across the double layer is almost equal to the ionization potential of the background gas atoms. Such structures can also appear as either concentric or non-concentric multiple double layers.
Our investigations show that the generation and dynamics of concentric as well as non-concentric multiple double layers show striking similarities. This proves that a common physical mechanism is at the origin of both of phenomena, in which the excitation and ionization electron-neutral impact reactions play the key role.
Roman Schrittwieser is also our point of contact for an Erasmus agreement with Innsbrück, and he has visited our Department several times over many years.
Everyone is welcome to the seminar! Coffee and tea will be served in the foyer afterwards.
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