Development of a beam probing system for measurement of density, temperature, and magnetic field of RFP plasma

Abstract

A hydrogen beam probing system developed for the REPUTE-1 reversed field pinch device is described. With this system, the plasma ion line density, the central ion temperature, and the magnetic field profile can be measured. Before being applied to the REPUTE-1 device, the probing system was tested on the TORIUT-5 tokamak and TORIUT-6 ultralow-q (ULQ) devices. The experimental results show the availability of the system. The measured line density agrees well with that measured by the microwave interferometry. The measurable density ranges from 1019 m−3 to 3×1020 m−3. A new method of magnetic field measurement which is effective and important for RFP plasmas is proposed. The resolution and the accuracy of this measurement have been confirmed by experiments on the TORIUT-5 device. Experimental results agree well with computation.

Recent results of ultra low q experiments in TORIUT-6 AND REPUTE-1

“…After carbonization, the quiescent phase lasts longer and V loop is reduced by 50% (from 100 V to 50 V). Figure 10 shows the temporal evolution of the line averaged ion density n lf measured with a hydrogen beam probing system with an energy of 10 keV [47].…”

“…Figure 12 shows the time evolution of the attenuated beam intensity of the hydrogen neutral beam. The attenuation is mainly due to the stripping by neutral gas and the charge exchange with plasma ions under the influence of the magnetic field [47]. Before and after the discharge the attenuation comes from the neutral gas, and during the discharge the attenuation comes mainly from the plasma ions.…”