Integrated Exhaust Scenarios with Actively Controlled ELMs
An integrated high performance scenario based on simultaneous feedback control of the averaged divertor neutral particle and power flux has been established at ASDEX Upgrade. This approach is fully compatible with the present tungsten wall coating covering about 65 % of the plasma facing components and intended for application in the envisaged full-tungsten experiment. In our experiments, particle exhaust and divertor temperature derived from thermoelectric currents were tuned by acting on gas puff and argon injection rates. The ELMfrequency is controlled by repetitive injection of small cryogenic deuterium pellets to avoid radiative instabilities occurring at low fELM and high radiated power and to control the ELM energy. No confinement loss is observed in this radiative type-I ELMy scenario with relatively flat density profiles. In contrast, similar type-III ELM scenarios achieved in hydrogen shows a relative confinement loss of 20 % as compared to the type-I phase. In parallel to pellets, alternative ELM trigger techniques like fast vertical plasma oscillations were developed and investigated as well. A particular experimental challenge for AUG conditions is to obtain a high pace making frequency.
Bibliographic Reference: An oral paper given at: 20th IAEA Fusion Energy Conference Organised by: International Atomic Energy Agency Held at: Centrtro de Fusao Nuclear, Vilamoura (PT)
Availability: Available from Association EURATOM-CEA, Département de Recherches sur la Fusion Contrôlée, CEA Cadarache, F-13108 St Paul-Lez-Durance, France Tel: (+33) 4 42 25 70 01; Fax: (+33) 4 42 25 64 21 E-mail: firstname.lastname@example.org
Record Number: 200518005 / Last updated on: 2005-03-15
Original language: en
Available languages: en