Suppression of Trapped Energetic Ions Driven Resistive Interchange Modes with Electron Cyclotron Heating in a Helical Plasma

The resistive interchange mode destabilized by the resonant interaction with the trapped energetic ions is fully suppressed when the injected power of electron cyclotron heating exceeds a certain threshold. It is shown for the first time that the complete stabilization of the energetic-particle-driven mode without relaxing the energetic particle (EP) pressure gradient is possible by reducing the radial width of the eigenmodes ${\delta }_w$, especially when ${\delta }_w$ narrows to a small enough value relative to the finite orbit width of EP.

Figure 1

Time evolutions of the zoomed waveforms of the magnetic fluctuations and the frequencies for the bursty EICs (a1) and continuous oscillatory mode (a2), the power spectra of the magnetic fluctuation (b) and the normalized integrated magnetic fluctuation with the varied ECH/ECW power (c).

Figure 2

Time evolutions of magnetic fluctuation ${\dot{b}}_{\theta }$, the port-through power of the PERP-NBI, PARA-NBI, and ECH (a) and the measured $n_e$, $T_e$ at the mode rational surface together with the volume-averaged beta of helically trapped EPs (b).

Figure 3

The deposited density profile from PERP-NBI of 1 MW at $t=4.006\mathrm{s}$, $t=4.74\mathrm{s}$, and $t=5.006\mathrm{s}$, estimated by fit3d code, respectively.

Figure 4

Time evolutions of electron temperature fluctuation profiles for $|\delta T_e|\ge 0.02\mathrm{keV}$ associated with the RIC (a) and the normalized magnetic fluctuations as the function of the radial width of the RICs, which are followed by the EICs (triangles) and which are not (dots) (b).

Figure 5

(a) Radial profiles of the coherences ${\gamma }_{\delta T_e}^2$ and phase differences between the magnetic fluctuation and $\delta T_e$, induced by the RIC without the ECH and with the ECH of 5 MW in shot 129647. (b) Radial profiles of the ${\gamma }_{\delta T_e}^2$ induced by the RIC without the ECH and with the ECH of 1.2 MW and 2.2 MW in shot 129595.

Figure 6

Time evolutions of $p_e$ (dots), $\nabla p_e$ (triangles), and the estimated $S$ at $\iota =1$ surface (a) and the ${\delta }_w$ of the RIC and oscillatory mode derived from the ${\gamma }_{\delta T_e}^2$ profiles (circles) and inferred from the measured plasma parameter change (dashed line), and the varied thresholds for the EIC excitation $f_{\mathrm{ow}}$ (squares and dash-dotted line), correspondingly (b).