High heat load on the surface of electrodes in DC arc plasma torches results in strong wear of electrodes. This takes place during the start up and shutting down procedure as well as during long-term running of the torch and results in arc voltage reduction. Such changes in voltage lead to a modification of the plasma jet properties and effect adversely reproducibility of deposits, which are undesirable for industrial applications. The present work offers a new approach to compensate cathode wear in DC arc gas stabilized plasma torches by using moveable anode. With this design of torch, the distance between the cathode tip and anode can be varied. Voltage fluctuation analysis show the possibility of a reasonable arc modification by approaching the nozzle to the cathode caused by a change of the flow field inside the arc chamber and the arc dynamics. Smaller cathode tip-nozzle distances result in higher arc voltage with reduced fluctuations accompanied by a positive effect on the plasma jet properties. Thus, the negative influence of cathode wear on generated plasma properties can be suppressed and the lifetime of the cathode can be extended by simple approaching the nozzle.

This paper focuses on development of the anode layer for SOFCs by plasma spraying. The composite (cermet) anode, developed by thermal spraying, consisted of nickel and YSZ. The effect of different plasma spraying technologies on the micro structural characteristics and the electrochemical behavior of the anode layer were investigated. Coatings were fabricated by spraying nickel-coated graphite or nickel oxide with YSZ using a Triplex II plasma torch under atmospheric conditions as well as a standard F4-torch under atmospheric or soft vacuum conditions. The investigations were directed in order to have an open micro porous structure, higher electrical conductivity and catalytic activity of anode deposits. Porosity was investigated by measuring the gas permeability. SEM and XRD technologies were applied to examine the morphology, microstructure and composition of the layers. Electrical conductivity measurements were carried out to determine ohmic losses within the anode layer. Most promising layers were analyzed by measuring the electrochemical behavior to obtain information about catalytic activity and performance.

Reproducibility of plasma spraying process and resulting deposits is one of the most essential requirements for its application in industrial environment. In most cases, only controlling process input parameters does not suffice for achieving stability and reproducibility of the process. Besides short time plasma instabilities such as arc root fluctuation, process deviations in longer time operations may arise due to electrodes wear and need to be identified by online diagnostics of the plasma spraying process. In this study two online diagnostic systems were employed to investigate the long-term behaviour of a F4-type plasma gun with a convergent and divergent Laval-nozzle. A Plasma Instability Analysis (PISA) system was applied to identify electrode wear and plasma fluctuation phenomena within the gun whereas Particle Flux Imaging (PFI) was used to correlate the electrode wear with the plasma jet characteristics at the nozzle exit. The long-term performance of electrodes was investigated under continuous operation and under periodic reignition of the torch. A good correlation between aberrations in the plasma process observed with PFI and changes in the frequency spectra detected by PISA was found.

Time-Resolved Emission (TRE) is a popular technique for non-invasive acquisition of time-domain waveforms from active nodes through the backside of an integrated circuit. [1] State-of-the art TRE systems offer high bandwidths (> 5 GHz), excellent spatial resolution (0.25um), and complete visibility of all nodes on the chip. TRE waveforms are typically used for detecting incorrect signal levels, race conditions, and/or timing faults with resolution of a few ps. However, extracting the exact voltage behavior from a TRE waveform is usually difficult because dynamic photon emission is a highly nonlinear process. This has limited the perceived utility of TRE in diagnosing analog circuits. In this paper, we demonstrate extraction of voltage waveforms in passing and failing conditions from a small-swing, differential logic circuit. The voltage waveforms obtained were crucial in corroborating a theory for some failures inside an 0.18um ASIC.