Author: You, H.J.
Paper Title Page
TUPOT018 Sheath Formation of a Plasma Containing Multiply Charged Ions, Cold and Hot Electrons, and Emitted Electrons 159
 
  • H.J. You
    NFRI, Daejon, Republic of Korea
  
  A model of sheath for­ma­tion was ex­tend­ed to a plas­ma con­tain­ing mul­ti­ply charged ions (MCIs), cold and hot elec­trons, and sec­ondary elec­trons emit­ted ei­ther by MCIs or hot elec­trons. The pre­sent study was mo­ti­vat­ed by the fact that the sec­ondary elec­tron yields are strong­ly de­pen­dent on the charge state of the ions and on the in­ci­dent en­er­gy of elec­trons. There­fore, the con­tri­bu­tions of the sec­ondary elec­tron emis­sions on the sheath for­ma­tion would be se­vere in ECRIS plas­mas where the charge state of ions is high and high­ly en­er­get­ic elec­trons exist. In the model, mod­i­fi­ca­tion of the “Bohm cri­te­ri­on” was given; there­by the sheath po­ten­tial drop and the crit­i­cal emis­sion con­di­tion were an­a­lyzed. The model cal­cu­la­tions were made main­ly on the ef­fects of the emit­ted elec­trons on the vari­a­tions of the sheath po­ten­tial drop, the par­ti­cle and heat flux to the wall, by which some ex­pla­na­tions for the ef­fect of sec­ondary elec­trons in ECR ion sources are given.  
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