This article presents a numerical approach to investigate the transpiration cooling problems with coolant phase change within porous matrix. A new model is based on the coupling of the two-phase mixture model (TPMM) with the local thermal nonequilibrium (LTNE), and used to describe the liquid coolant phase change and heat exchange processes in this article. The effects of thermal conductivity, porosity, and sphere diameter of the porous matrix on the temperature and saturation distributions within the matrix are studied. The results indicate that an increase in the porosity or sphere diameter can lead to an area dilation of two-phase region and a rise of liquid temperature; whereas an increase in the thermal conductivity of the porous matrix results only in a rise of liquid temperature, but drops of solid temperature and temperature gradient on the hot surface. The influence of hot surface pressure on cooling effect is discussed by numerical simulations, and numerical results show that the effect of the transpiration cooling will be worse under higher pressure. The investigation also discovers an inverse phenomenon to the past investigations on the transpiration cooling without coolant phase change, namely in two-phase region, coolant temperature may be higher than solid temperature. This inversion can be captured only by the new LTNE-TPMM.

The experiments were carried out to study the coupling characteristics of the I-port antenna in the ion cyclotron range of frequencies (ICRF) in EAST. The dependencies of the coupling resistance on various parameters including the antenna position, the central electron density, gas injection and the antenna phasing have been studied. The results obtained show that the experimental data are consistent with theoretical simulations. We find that the antenna loading resistance decreases sharply at the L-H transition due to the change of the plasma density profiles in the scrape-off layer (SOL). The effect of the low hybrid wave (LHW) on the ICRF coupling during the H-mode is observed. The theoretical interpretation of the results is discussed, together with the efficient methods to optimize the coupling efficiency.

We propose and demonstrate an all-fiber actively mode-locked laser producing optical vortex pulses with high efficiency and a tunable repetition rate. Both vectorial and scalar optical vortices, i.e., cylindrical vector beams and orbital angular momentum beams, have been generated. Highly efficient mode conversion is realized by introducing a two-mode long-period fiber grating into the laser cavity as a mode converter with low insertion loss. A two-mode fiber Bragg grating is employed as a mode selector, a spectrum filter and an output mirror. A LiNbO3 Mach–Zehnder intensity modulator served as a mode-locker to achieve active harmonic mode-locking. The slope efficiency increases from 10.24% to 12.61% with the repetition rate of the pulse train flexibly tuned from 15.65 MHz at the fundamental mode-locking to 626 MHz at the 40th order harmonic mode-locking with superior stability. Switching between vectorial and scalar optical vortices at different repetition rates is realized through the intra-cavity state of polarization control.