Ignitor

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Heating

Physics

According to its proponents, ohmic heating leads the quasi-impurity-free 50% deuterium-50% tritium Ignitor plasma to ignition in an unsteady scenario including a fast ramp-up of the plasma current. However, an Ion Cyclotron Resonant Heating (ICRH) system has also been added to accelerate the achievement of ignition as well as to access the H- and the I-regimes.
In Ignitor the available heating power would be provided by a 18-24 MW of ion cyclotron heating plus the ohmic power
[1]. In order to reach the envisaged peak density shortly after the end of the current ramp, when ignition is expected to occur, a high speed injector (producing pellets with velocities » 4 Km/s) has been included in the machine design. Besides ensuring fast core fuelling and density profile control, the injector also provides time dependent burn control [1], [4].
In the Ignitor experiment, the ICRH waves are planned to be used as a tool to control the plasma temperature, in particular to accelerate the achievement of ignition in the extended first wall configuration, and to facilitate the H-mode transition in the double X-point configuration
[3].
The ICRH system has been conceived with a modular configuration (two modules, each serving two antennas) to optimize the coupling of the RF (radio-frequency) power to the plasma in different regimes. The RF module, in turn, is based on 4 high power generators and is able to operate in the frequency range 80-120 MHz generating a total power up to 8 MW at the central frequency of 80 MHz.
Furthermore, once the full complement of RF heating is provided, then significant amount of fusion power could be produced in D- 3He reactions, thus beginning the exploration of tritium-poor burn experiments
[2].


1) B. Coppi et al, Nucl. Fusion 41, 1253 (2001)
2) F. Bombarda et al, Braz. J. Phys. 34, 1786 (2004)
3) B. Coppi et al, Overview Paper OV/P-02, Proceedings of the 24 th IAEA Fusion Energy Conference, San Diego, US, 8-13/10/2012
4) B. Coppi et al, Overview Paper OV/P-02, Proceedings of the 23 rd IAEA Fusion Energy Conference, Daejeon, Republic of Korea, 11-16/10/2010


 
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