Tubes, secondary-electron conduction

There exist no free or Fermi electrons in glass, which is considered to be a semiconductor with a very low specific conductivity (10 to 10 ohm cm. i). The question then arises Where do the secondary electrons originate in ozonizer tubes when the discharge enters the self-maintained region ... 

The variable magnetic field that is created confines the ions and the electrons to an annular path. As the medium becomes more and more conducting, by appearance of an Eddy current, temperature increases considerably by the Joule effect. The device behaves similar to the secondary coil of a short-circuited transformer. The plasma is isolated from the torch wall by a gaseous sheath of non-ionized argon, which is injected by an external tube concentric to the previous one and is used to keep quartz wall cool. 

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