ABSTRACT
B ecause p lasm a is an ion ized m edium , the key p rocess in p lasm a is ionization . T his m eans that a neu tral a tom o r m olecu le is converted in to a positive ion and also an e lec tron , as illustrated in F igure 2.1 (a). T he m ain tw o partic ipan ts o f the ion ization p rocess, electrons and positive ions, are at the sam e tim e the m ost im portan t charged partic les in p lasm a. T he principal characteristics and elem en tary p rocesses o f the elec trons and positive ions as w ell as som e characteristics o f negative and com plex ions w ill be d escribed in th is section . B ehav io r and elem en tary p rocesses o f excited m olecu les and o th er active neutral com ponen ts o f p lasm a w ill be d iscussed in C hap ter 3.
