The Ignitor machine can access a significant variety of plasma regimes, thanks to its high magnetic fields and plasma currents and to the flexibility of its poloidal magnetic field system, with a characteristic split central solenoid that can produce both an extended limiter configuration and a divertor-like double X-point configuration. The machine design is guided by the criterion of maximizing the average poloidal field to ensure macroscopic plasma stability at ignition. The path to ignition conditions was simulated with the IETTO transport code for both L-mode and H-mode regimes. It is also shown that with a modest injection of ICRH power, ignition can be reached earlier than by ohrnic heating alone, thus allowing the investigation of the relevant burning plasmas over times that exceed the current redistribution time. Near ignition, internal modes close to ideal marginal stability could be excited, according to linearized theory, under the most pessimistic conditions, but their development is shown to be strongly influenced by non linear effects, even at very low values of the mode amplitude. The BALDUR transport code was used to simulate the approach to ignition when reversed shear conditions with peaked density profiles are produced through appropriate current rarnping. The importance of particle density profile control is confirmed, and the optimal auxiliary heating power to accelerate ignition is evaluated.

Physical Regimes Accessible to the Ignitor Experiment and Relevant Theoretical Developments

2002

Abstract

The Ignitor machine can access a significant variety of plasma regimes, thanks to its high magnetic fields and plasma currents and to the flexibility of its poloidal magnetic field system, with a characteristic split central solenoid that can produce both an extended limiter configuration and a divertor-like double X-point configuration. The machine design is guided by the criterion of maximizing the average poloidal field to ensure macroscopic plasma stability at ignition. The path to ignition conditions was simulated with the IETTO transport code for both L-mode and H-mode regimes. It is also shown that with a modest injection of ICRH power, ignition can be reached earlier than by ohrnic heating alone, thus allowing the investigation of the relevant burning plasmas over times that exceed the current redistribution time. Near ignition, internal modes close to ideal marginal stability could be excited, according to linearized theory, under the most pessimistic conditions, but their development is shown to be strongly influenced by non linear effects, even at very low values of the mode amplitude. The BALDUR transport code was used to simulate the approach to ignition when reversed shear conditions with peaked density profiles are produced through appropriate current rarnping. The importance of particle density profile control is confirmed, and the optimal auxiliary heating power to accelerate ignition is evaluated.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.12079/4381
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