MHD stability analysis of type II ELMs in ASDEX Upgrade
نویسنده
چکیده
We investigated the differences between type I and type II edge localized modes (ELMs) in ASDEX Upgrade using the MHD stability analysis. When plasma conditions are changed from typical type I ELMy conditions to type II ELMy conditions, the character of the edge instabilities change. With increased triangularity and edge safety factor, the low-n peeling–ballooning mode becomes more stable and more localized to the edge region. We find the same mode localization effect in almost double null configuration. When the plasma density is increased, the access to the second stability of the high-n ballooning modes is closed. The changes in the stability properties give a qualitative explanation to the observed small amplitude of the type II ELMs. PACS numbers: 52.35.Py
منابع مشابه
Magnetohydrodynamic stability analyses of tokamak edge plasmas
s of publications 1-5: 1. An ELMy ASDEX Upgrade plasma equilibrium is reconstructed taking into accountthe bootstrap current. The peeling mode stability of the equilibrium is numericallyanalysed using the GATO [1] code, and it is found that the bootstrap current candrive the plasma peeling mode unstable. A high-n ballooning mode stability analysisof the equilibria revealed that,...
متن کاملFirst observation of edge localized modes mitigation with resonant and nonresonant magnetic perturbations in ASDEX Upgrade.
First experiments with nonaxisymmetric magnetic perturbations, toroidal mode number n=2, produced by newly installed in-vessel saddle coils in the ASDEX Upgrade tokamak show significant reduction of plasma energy loss and peak divertor power load associated with type-I edge localized modes (ELMs) in high-confinement mode plasmas. ELM mitigation is observed above an edge density threshold and is...
متن کاملTransport analysis and modelling of high radiation and high density plasmas at ASDEX Upgrade
Future fusion reactors will require high divertor and core radiation by impurity seeding to limit divertor heat loads. In addition, high core densities are required to maximize the fusion power. A well established technique to reduce heat loads on divertor target plates is to insert low and medium Z impurities in the plasma to convert the heat flux into radiation [1]. Radiative cooling by nitro...
متن کاملHigh temporal and spatial resolution reflectometry investigations of type-I ELMs induced edge barrier collapse at ASDEX Upgrade
The edge barrier collapse induced by spontaneous and pellet triggered ELMs has been characterized by means of a new technique based on the reflectometry group delay. The analysis of the behaviour of the density layers at the plasma edge revealed small differences between the two types of ELMs. With this technique we are able to detect profile steepening and fuelling effects due to pellet inject...
متن کاملSplashing and boiling mechanisms of melt layer losses of PFCs during plasma instabilities
Due to excellent thermo-mechanical properties, tungsten (W) is considered as a promising divertor material in ITER, full divertor in JET, first wall in DEMO and ASDEX Upgrade. During plasma disruptions and ELMs the W material can be severely damaged because of macroscopic melt losses resulting in short lifetime and plasma contamination. Therefore, understanding the underlying forces and physica...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 2003