Divertor Thomson scattering (DTS) and laser-induced fluorescence (LIF) are both laser aided diagnostics well suited to combination with common probing and collecting optics that are the most sophisticated and expensive part of any ITER optical diagnostic system. The combination of DTS and LIF are used for simultaneous measurement of local electron (Te, ne), ion (Ti, nHeII) and atom (nHeI, nH(D,T)) parameters and provide basic information on rates of electron and ion processes to allow basic understanding of the physics of divertor plasma detachment. The measured parameters permit the calculation of rates of ionization and recombination using Te, ne, Ti, ni, nHeI and nH(D,T); emission intensity—Te, ne, ni, nHeI and nH(D,T); frictional force of the plasma flow due to collisions with neutrals—Ti, ni, T0, nHeI and nH(D,T) and pressure of the incoming plasma flow—Te, ne, Ti and ni. The paper discusses the benefits of DTS and LIF integration, suggests new approaches to the estimation of DTS capability, LIF implementation and possibilities for further diagnostic development.
A new mathematical processing method for current signals from surface dielectric barrier discharge in conditions of high noise is suggested. This technique is based on the analysis of isolated microdischarge parameters: charge transfer, impulse duration, and voltage/phase, followed by statistical analysis. Research was carried out on surface dielectric barrier discharge units with a copper thin corona electrode on a 1 mm aluminum nitride barrier. Four modes with the corresponding rms-voltages of 1.8, 2.0, 2.2, and 2.4 kV were considered. Distributions of microdischarge parameters and overall phase characteristics were collected.
The cathode plasma is a specific transition region in the Hall Effect Thruster (HET) discharge that localizes between the strongly magnetized acceleration layer (magnetic layer or B-layer) and non-magnetized exhaust plume. Cathode plasma provides a flow of electron current that supplies losses in the magnetic layer (due to ionization, excitation, electron-wall interactions, etc.). The electrons' transport in this region occurs in collisionless mode through the excitation of plasma instabilities. This effect is also known as "anomalous transport/conductivity". In this work, we present the results of a 2d (drift-plane) kinetic simulation of the HET discharge, including the outside region that contains cathode plasma. We discuss the process of cathode plasma formation and the mechanisms of "anomalous transport" inside it. We also analyze how fluid force balance emerges from collisionless kinetic approach. The acceleration mechanism in Hall Effect Thrusters (HETs) is commonly described in terms of force balance. Namely, the reactive force produced by accelerated ions has the same value as Ampère's force acting on a drift current loop. This balance written in integral form provides the basis for quantitative estimations of HETs' parameters and scaling models.
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