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Sawtooth stabilisation for more than two seconds (corresponding to the maximum heating pulse length) can be achieved in TEXTOR in deuterium discharges by means of neutral beam co-injection. The parameter domain where sawtooth-free operation prevails is larger with D(0) than with H(0) injection. The sawtooth period is found to be much more resistant to changes by counter beams. Although ICRH can stretch the sawtooth period, it never succeeds in full stabilisation. In combination with NI, however, ICRH is capable of extending the operational stabilised domain. This paper presents the experimental data, shows that q stays below 1 in the sawtooth-free phase and interprets the results in terms of stabilisation of the resistive internal m = 1 mode by trapped energetic ions. The creation of trapped hot-ions populations strongly peaked inside the q = 1 surface is apparently essential for stabilisation. The differences between NI-co, NI-cou and ICRH can be understood by the differences in power deposition profiles in TEXTOR.

Additional information

Authors: ONGENA J, Ecole Royale Militaire, Bruxelles (BE);CORNELISSEN P, Ecole Royale Militaire, Bruxelles (BE);MESSIAEN A M, Ecole Royale Militaire, Bruxelles (BE);WEYNANTS R R, Ecole Royale Militaire, Bruxelles (BE);CONRADS H, Institut für Plasmaphysik, Kernforschungsanlage Jülich GmbH, Jülich (DE);KEVER H, Institut für Plasmaphysik, Kernforschungsanlage Jülich GmbH, Jülich (DE)
Bibliographic Reference: Paper presented: 17th European Conference on Controlled Fusion and Plasma Heating, Amsterdam (NL), June 25-29, 1990
Availability: Available from (1) as Paper EN 35808 ORA
Record Number: 199011637 / Last updated on: 1994-12-02
Original language: en
Available languages: en