Predictive modelling of ELMy H-modes with a new theory-motivated model for ELMs
A new model for the type I ELMy H-mode based on linear ballooning stability theory is presented. The model can be written as a linear differential equation for the amplitude of an unstable ballooning mode and is coupled to a system of transport equations. The differential equation for the ballooning mode amplitude has two terms-one representing the growth rate of the perturbation and one controlling the decay rate of the mode and driving the mode amplitude towards the level of background fluctuations. A critical pressure gradient limit is used to control whether the growth rate differs from zero. When coupled to a JETTO transport simulation, the model qualitatively reproduces the experimental dynamics of a type I ELMy H-mode, including an edge localized mode (ELM) frequency that increases with the external heating power. This paper also discusses why the linear ballooning model, in the first place, produces discrete oscillations when coupled to a transport simulation rather than a stationary state with a slightly enhanced ballooning mode amplitude.
Bibliographic Reference: An article published in: Plasma Physics and Controlled Fusion 46 (2004) A249�A256 PII: S0741-3335(04)70003-2
Availability: This article can be accessed online by subscribers, and can be ordered online by non-subscribers, at: DOI: 10.1088/0741-3335/46/5A/027
Record Number: 200513136 / Last updated on: 2005-06-06
Original language: en
Available languages: en