Real-time Control Logic Research Articles

Adaptive tuned dynamic vibration absorbers working with MR elastomers

This paper presents the development of a new Adaptive Tuned Dynamic Vibration Absorber (ATDVA) working with magnetorheological elastomers (MREs). The MRE materials were fabricated by mixing carbonyl iron particles with silicone rubber and cured under a strong magnetic field. An ATDVA prototype using MRE as an adaptable spring was designed and manufactured. The MRE ATDVA worked in a shear mode and the magnetic field was generated by a magnetic circuit and controlled through a DC power supply. The dynamic performances or the system transmissibility at various magnetic fields of the absorber were measured by using a vibration testing system. Experimental results indicated that this absorber can change its natural frequency from 35Hz to 90Hz, 150% of its basic natural frequency. A real time control logic is proposed to evaluate the control effect. The simulation results indicate that the control effect of MRE ATDVA can be improved significantly.

Controllability of large bootstrap current fraction plasmas in JT-60U

Controllability of plasmas with a large bootstrap current fraction (fBS) has been investigated in JT-60U. Real time control logic for avoidance of collapses by pressure profile control through the toroidal rotation has been newly installed for the long sustainment of reversed magnetic shear plasmas. The new real time control logic can control the injection timing of the neutral beam based on the real time detection of the minimum value of safety factor (qmin) using the motional Stark effect diagnostic. Using the real time control logic, the weak reversed magnetic shear plasma with fBS ∼ 70% is sustained for ∼8 s. In such a plasma, dynamic change in the current profile, especially qmin, which was induced by the change in the pressure profile at the internal transport barrier (ITB) through the rotation control, was observed. The response of qmin to the change in the ion temperature gradient at the ITB for large fBS plasmas is stronger than that for smaller fBS plasmas.