Electrons and ions both contribute to current in proportion to their mobility in the system. Instead, the current in each direction can be due to combinations of the electric fields in all the other directions. All forms of electromagnetic radiation can be transmitted through vacuum. Wave characterized by combined oscillations of both electric and magnetic fields. The particle equivalent is the photon.
Electrons orbit around the positively charged nucleus in an atom.
The configuration of electrons around an atom determines its chemical properties. The positron is the antiparticle to the electron, and is identical except for having a positive charge. The ions react with impurities on the walls of the tokamak and help remove them from the chamber. For instance, Alcator C-mod typically applies ECDC for a few days prior to beginning a campaign, and a few hours before each day's run. This is known as electron cyclotron emission, and can be measured to help diagnose a plasma.