By installing an X-mode polarized Q-band (32-56 GHz) reflectometry at the low field side on EAST, the zero density cutoff layer was determined and the edge density profile was measured in normally operating plasmas. A Monte Carlo procedure has been developed to analyze the density profiles by considering the error of time delay measured by reflectometry. By combining this Q-band and previously developed V-and W-band reflectometries, the density profiles from edge to core can be measured in most EAST experiments. The line integrated densities deduced from density profiles measured by reflectometry are consistent with those directly measured by a horizontal interferometer. The density pedestal measured by reflectometry shows a clear crash during an ELM (edge localized mode) event, after which the pedestal gradually increases and recovers in 10 ms and then remains little changed up to the next ELM.

A microwave reflectometry system operating in the V-band frequency with extraordinary mode polarization has been developed on the EAST tokamak. The reflectometry system, using a voltage-controlled oscillator (VCO) source driven by an arbitrary waveform generator with high temporal resolution, can operate for the density profile measurement. The result of the bench test shows that the output frequency of the VCO has a linear dependence on time. The dispersion of reflectometry system is determined and reported in this paper. The evolution of a pedestal density profile during the L-H transition is observed by the reflectometry in H-mode discharges on EAST tokamak. A frequency synthesizer is used to replace the VCO as microwave source for density fluctuation measurements. The level of density fluctuation in the pedestal shows an abrupt decrease when the plasma enters into H-mode. A coherent mode with a frequency of about 100 kHz is observed and the mode frequency decreases gradually as the pedestal evolves.

A compact torus injection system, KTX-CTI, has been developed for the planned injection experiments on the Keda Torus eXperiment (KTX) reversed field pinch (RFP) device to investigate the physics and engineering issues associated with interaction between a compact torus (CT) and RFP. The key interests include fueling directly into the reactor center, confinement improvement, and injection of momentum and helicity into the RFP discharges. The CT velocity and mass have been measured using a multichannel optical fiber interferometer, and for the first time the time evolution of CT density profile during CT propagation is obtained. The number of injected particles, the CT velocity and density on the discharge parameters have been characterized: the maximum hydrogen CT plasma mass, m_CT, is 50 μg, corresponding to 30% of the mass in a typical KTX plasma; the CT velocity exceed 120 km/s. It is firstly observed that multiple CTs can be produced and emitted during the very short period (<100 μs) in one discharge, which is significant for the future study of repetitive CT injection, even with an ultra-high frequency.