Parallel impurity dynamics in the TJ-II stellarator by Alonso, J, Velasco, J, Calvo, I, Estrada, T, Fontdecaba, J, García-Regaña, J, Geiger, J, Landreman, M, McCarthy, K, Medina, F, Milligen, B, Ochando, M, Parra, F, Team, TTJ-II, Team, TW-X