Vignyana Kathegalu

Plasma, the 4th state of matter after solid, liquid and gas comprises of ions, electrons and neutrals. Plasma is quasi-neutral, i.e., it has nearly same number of ions and electrons in unit volume. Ions, electrons and neutrals may have same or different temperatures. The motion of ions and electrons can be controlled by external and self-generated electric and magnetic fields. Plasma is a good conductor of electricity and shows collective behaviour. Very high temperature (~ few keV) plasmas can be used to fuse nuclei of deuterium and tritium to do nuclear fusion. A combined effort of seven countries (EU as one country) in building the ITER tokamak in France is under progress, where India is a full partner. Low temperature (~ eV) plasmas with similar ion, electron and neutral temperatures can be used as an intense heat source. Such a heat source can dissociate large molecules, and hence such a plasma source is used for waste treatment. Low temperature (electrons ~ few eV, ions and neutrals ~ 0.1 eV) plasmas, where electron temperature is more than ion and neutral temperatures, are chemically very active and can be used for surface modification. The talk will cover various aspects of plasmas and its applications.