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FIZIKA A 17 (2008) 2 , 67-70
 
LETTER TO THE EDITOR
IMPURITY OF DUST-ACOUSTIC PLASMA INSTABILITY DUE TO TRAPPED IONS
KH. H. EL-SHORBAGY
Institut für Theoretische Physik IV and Excellence Centre for Plasma Science and Astrophysics,
Fakultät für Physik und Astronomie, Ruhr-Universität Bochum, D-44780 Bochum, Germany
Permanent address: Plasma Physics Department, Nuclear Research Center,
Atomic Energy Authority, Cairo, Egypt
Received 23 August 2007; Revised manuscript received 16 January 2008
Accepted 3 September 2008 Online 17 October 2008
We are investigating the low-frequency electrostatic perturbation in tokamak
plasma in the "banana" regime by taking account the effects of the Coulomb
collision on the trapped ion. We consider the dust-acoustic plasma instability
caused by the presence of ion impurities. We point out that the presence of
impurity ions, especially if their density gradient is different from the dust
plasma density gradient, i.e., if they are peaked near the wall, can generate a
new instability which is difficult to stabilize and which leads to diffusion of
the impurities into the dust-acoustic plasma.
PACS numbers: 52.35.Py, 52.25.Zb, 52.25.Vy
UDC 533.95, 533.922
Keywords: tokamak plasma, "banana" regime, dust-acoustic plasma instability,
diffusion of impurities
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