NIFS-997

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Author(s):

O. Mitarai, A. Sagara, R. Sakamoto, N. Yanagi, T. Goto, S. Imagawa, O. Kaneko, and A. Komori

Title:

The high density ignition in FFHR helical reactor by neutral beam injection (NBI) heating

Date of publication:

Nov. 2010

Key words:

22 IAEA Fusion Energy Conference, FTP/P6-19

Abstract:

Actual heating systems have not been considered yet for reaching the ignition regime in FFHR helical reactor. Although NBI heating is a first candidate to access the low density and high temperature ignition regime, it is uncertain whether such system can be used to access the high density and low temperature ignition regime. In this work the foreseeable NBI energy of ~1.5 MeV is assumed and examined for reaching both ignition regimes in the FFHR. Together with the stabilizing technique of the thermal instability by the proportional-integral-derivative (PID) control algorithm based on the fusion power, we propose the new operation scenario to access the high-density ignition regime using neutral beam heating system with ~1.5 MeV energy. In this new scenario the density is kept at the low value less than ~4x10^20 m^-3 to ensure the neutral beam penetration and the operating point passes near the saddle point on Plasma Operation Contour (POPCON) map. Above the density of 10^20 m^-3, high-density ignition is accessed by alpha heating after turning off NBI injection.

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