Wandong Liu

La2NiO4 tubular membrane reactor for conversion of methane to syngas

Abstract La 2 NiO 4 tubular membranes of relative density over 92% were used to separate oxygen from air and facilitate the partial oxidation of methane to H 2 and CO at 900xa0°C. When methane was fed into a tube of inner surface area 5.11xa0cm 2 at a rate of 10.5xa0ml/min, methane throughput conversion was 89%, CO selectivity 96%, H 2 /CO ratio 1.5, and the equivalent oxygen flux was 6.8xa0ml/min. The surface of the La 2 NiO 4 membrane exposed to CH 4 decomposed into La 2 O 3 and Ni, while the surface in contact with air remained almost unchanged. It is suggested that the conversion of methane in the membrane reactor involves the reforming of methane by the H 2 O and CO 2 catalyzed by nickel.

Progress of the Keda Torus eXperiment Project in China: design and mission

The Keda Torus eXperiment (KTX) is a medium-sized reversed field pinch (RFP) device under construction at the University of Science and Technology of China. The KTX has a major radius of 1.4 m and a minor radius of 0.4 m with an Ohmic discharge current up to 1 MA. The expected electron density and temperature are, respectively, 2 × 1019 m−3 and 800 eV. A combination of a stainless steel vacuum chamber and a thin copper shell (with a penetration time of 20 ms) surrounding the plasma provides an opportunity for studying resistive wall mode instabilities. The unique double-C design of the KTX vacuum vessel allows access to the interior of the KTX for easy first-wall modifications and investigations of power and particle handling, a largely unexplored territory in RFP research leading to demonstration of the fusion potential of the RFP concept. An active feedback mode control system is designed and will be implemented in the second phase of the KTX program. The recent progress of this program will be presented, including the design of the vacuum vessel, magnet systems and power supplies.

Observation of radial propagation of electrostatic fluctuations on KT-C tokamak

The radial wavenumber spectra of electrostatic fluctuations measured by Langmuir probe arrays on the KT-5C tokamak show a quasimode-like structure which results in a net radial outward propagation of the turbulent fluctuations. The power-averaged radial wavenumber is approximately constant in the core region and increases near the limiter. The radial wavenumber spectral width stays nearly constant from core to edge and is about two times greater than the poloidal wavenumber spectral width. The measured fluctuation levels and wave action fluxes are in good agreement with model predictions (Mattor N and Diamond P H 1994 Phys. Plasmas 1 4002, Mattor N 1995 Phys. Plasmas 2 766) which suggest that drift wave propagation could be a source of edge turbulence.

Effects of electrode biasing on fluctuations and transport in the KT-5C tokamak

Electrode biasing experiments are carried out on the KT-5C tokamak to investigate the effects of the radial electric field E/sub r/ on turbulence. A modestly enhanced E/sub r/ gradient layer is formed at the plasma edge by the electrode biasing. In the E/sub r/ gradient layer, reductions in the fluctuation amplitude, radial correlation length and turbulent particle flux are observed. These results support the theoretical models on the turbulence suppression by decorrelation due to E /spl times/ B flow shear.

Design of interferometer system for Keda Torus eXperiment using terahertz solid-state diode sources.

A solid-state source based terahertz (THz) interferometer diagnostic system has been designed and characterized for the Keda Torus eXperiment (KTX). The THz interferometer utilizes the planar diodes based frequency multiplier (X48) to provide the probing beam at fixed frequency 0.650 THz, and local oscillator is provided by an independent solid-state diode source with tunable frequency (0.650 THz +/- 10 MHz). Both solid-state sources have approximately 1 mW power. The planar-diode mixers optimized for high sensitivity, ∼750 mV/mW, are used in the heterodyne detection system, which permits multichannel interferometer on KTX with a low phase noise. A sensitivity of ⟨nel⟩min = 4.5 × 10(16) m(-2) and a temporal resolution of 0.2 μs have been achieved during the initial bench test.

Simulation of feedback control on tearing modes using different sensors in a reversed field pinch and application to the Keda Torus eXperiment

Feedback control of dynamo tearing modes (TMs) in a reversed field pinch (RFP) using radial field sensors has been achieved in RFX-mod (Zanca et al 2012 Plasma Phys. Control. Fusion 54 124018). In this paper a simulation, performed with the RFXLocking code (Zanca 2009 Plasma Phys. Control. Fusion 51 015006), is presented with the purpose of discovering the dependence of TM feedback on the type (radial, poloidal and toroidal) and location of the sensors. An arrangement of the latter inside the stabilizing shell is considered. Moreover, the impact of different sensors of the sideband harmonics, produced by a uniform grid of active coils located outside the shell, is investigated. The simulations consider the layout of the Keda Torus eXperiment (KTX), a large device under construction in Hefei designed to operate in the RFP configuration. Therefore, this work can give important indications to the project of the feedback control system in the KTX. The most important result is that radial field sensors turn out to be equivalent to the poloidal and toroidal ones only upon the removal of the aliasing coming from the coils sideband harmonics.

Thomson scattering measurement of gold plasmas produced with 0.351 μm laser light

Detailed measurements of gold plasmas produced with 0.351 μm laser light are reported. The temporal and spatial variations of ZTe are obtained in the case that pump intensities are 6.5×1013 and 1.4×1014u200aW/cm2. The experimental results are qualitatively consistent with two nonlocalized absorption models.

The eddy current probe array for Keda Torus eXperiment

In a reversed field pinch device, the conductive shell is placed as close as possible to the plasma so as to balance the plasma during discharge. Plasma instabilities such as the resistive wall mode and certain tearing modes, which restrain the plasma high parameter operation, respond closely with conditions in the wall, in essence the eddy current present. Also, the effect of eddy currents induced by the external coils cannot be ignored when active control is applied to control instabilities. One diagnostic tool, an eddy current probe array, detects the eddy current in the composite shell. Magnetic probes measuring differences between the inner and outer magnetic fields enable estimates of the amplitude and angle of these eddy currents. Along with measurements of currents through the copper bolts connecting the poloidal shield copper shells, we can obtain the eddy currents over the entire shell. Magnetic field and eddy current resolutions approach 2 G and 6 A, respectively. Additionally, the vortex electric field can be obtained by eddy current probes. As the conductivity of the composite shell is high, the eddy current probe array is very sensitive to the electric field and has a resolution of 0.2 mV/cm. In a bench test experiment using a 1/4 vacuum vessel, measurements of the induced eddy currents are compared with simulation results based on a 3D electromagnetic model. The preliminary data of the eddy currents have been detected during discharges in a Keda Torus eXperiment device. The typical value of toroidal and poloidal eddy currents across the magnetic probe coverage rectangular area could reach 3.0 kA and 1.3 kA, respectively.

Dual-role plasma absorption probe to study the effects of sheath thickness on the measurement of electron density

A sensitive plasma absorption probe (PAP) is reported for measuring electron density in processing plasmas. The sheath formed around the probe tip is important for the resonance of surface waves. For determining the absolute electron density from the absorption frequency of the sensitive PAP, a proper value of sheath thickness relative to the Debye length is required to be assigned in the data processing. In this paper, a dual-role PAP has been proposed to study the effects of sheath thickness on the measurement of electron density. It is used as a Langmuir probe and a sensitive PAP simultaneously. Based on these two functions, the sheath thickness is calibrated before the measurement of electron density. The calibrated value is assigned in the data processing to replace the fitting coefficient used in the previous work. Therefore, the measurement error caused by an inaccurately assigned sheath thickness can be minimized effectively. Because of the bi-functional characteristic, the dual-role PAP is an independent diagnostic tool.

Compatible operation of the power system for steady state and pulse modes in a magnetic torus KT-5D

Compatible operation of steady state mode and pulse mode is realized in the KT-5D device. New power supplies with the operation control systems for the steady state toroidal magnetic field as well as for the vertical field are added, and the rf wave injection systems for sustaining steady state plasmas are upgraded. After the modification, the device now can work not only as a tokomak with pulsed plasma currents as it was but also as a simple magnetized torus with steady state plasma discharges. It allows more flexible and efficient experimental researches on the magnetically confined plasmas to be carried on in the same device.