Application of dust grains and Langmuir probe for plasma diagnostics Y. A. Ussenov, T. S. Ramazanov, K. N. Dzhumagulova and M. K. Dosbolayev EPL, 105 1 (2014) 15002 Published online: 29 January 2014 DOI: 10.1209/0295-5075/105/15002