A new experimental setup for flow rate measurement of gases through microsystems is presented. Its principle is based on two complementary techniques, called droplet tracking method and constant-volume method. Experimental data on helium and argon isothermal flows through rectangular microchannels are presented and compared with computational results based on a continuum model with second-order boundary conditions and on the linearized kinetic BGK equation. A very good agreement is found between theory and experiment for both gases, assuming purely diffuse accommodation at the walls. Also, some experimental data for a binary mixture of monatomic gases are presented and compared with kinetic theory based on the McCormack model.

Articles you may be interested inImpact of the gas-surface scattering and gas molecule-molecule interaction on the mass flow rate of the rarefied gas through a short channel into a vacuum J. Vac. Sci. Technol. A 28, 1393 (2010); 10.1116/1.3504596Rarefied gas flow through a thin slit into vacuum simulated by the Monte Carlo method over the whole range of the Knudsen number Experimental and numerical modeling of rarefied gas flows through orifices and short tubes AIP Conf.A rarefied gas flow into vacuum through a tube of finite length is investigated over the whole range of gas rarefaction by the direct simulation Monte Carlo method. The nonequilibrium effects at the inlet and outlet of the tube have been considered by including in the computational domain large volumes of the upstream and downstream reservoirs. Results for the dimensionless flow rate and for the flow field are presented for a wide range of the gas rarefaction and for various values of the length to radius ratio in the range from 0 to 10. The influence of the gas-surface interaction model, as well as the effect of the intermolecular potential model on the gas flow, is examined. A good agreement has been obtained between the present numerical results and the corresponding experimental ones available in the literature.

The 2014–2016 JET results are reviewed in the light of their significance for optimising the ITER research plan for the active and non-active operation. More than 60 h of plasma operation with ITER first wall materials successfully took place since its installation in 2011. New multi-machine scaling of the type I-ELM divertor energy flux density to ITER is supported by first principle modelling. ITER relevant disruption experiments and first principle modelling are reported with a set of three disruption mitigation valves mimicking the ITER setup. Insights of the L–H power threshold in Deuterium and Hydrogen are given, stressing the importance of the magnetic configurations and the recent measurements of fine-scale structures in the edge radial electric. Dimensionless scans of the core and pedestal confinement provide new information to elucidate the importance of the first wall material on the fusion performance. H-mode plasmas at ITER triangularity (H  =  1 at βN ~ 1.8 and n/nGW ~ 0.6) have been sustained at 2 MA during 5 s. The ITER neutronics codes have been validated on high performance experiments. Prospects for the coming D–T campaign and 14 MeV neutron calibration strategy are reviewed.

A computational and experimental study has been performed for the investigation of fully developed rarefied gas flows through channels of circular, orthogonal, triangular, and trapezoidal cross sections. The theoretical-computational approach is based on the solution of the Bhatnagar-Gross-Krook kinetic equation subject to Maxwell diffuse-specular boundary conditions by the discrete velocity method. The experimental work has been performed at the vacuum facility "TRANSFLOW," at Forschungszentrum Karlsruhe and it is based on measuring, for assigned flow rates, the corresponding pressure differences. The computed and measured mass flow rates and conductance are in all cases in very good agreement. In addition, in order to obtain some insight in the flow characteristics, the reference Knudsen, Reynolds, and Mach numbers characterizing the flow at each experimental run have been estimated. Also, the pressure distribution along the channel for several typical cases is presented. Both computational and experimental results cover the whole range of the Knudsen number.

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