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Helicon plasma sources are widely used in basic plasma science, as well as for materials processing. These plasmas typically operate at high gas fill pressure, and therefore have significant densities of neutral particles. However, the role of neutrals in the overall plasma dynamics, such as ion flows, remains poorly understood. There are at least two possible mechanisms for neutrals to influence ion flows. One is an FxB drift, where F is the force exerted on ions by neutrals through collisions. The second is through Pedersen conductivity which is dependent on the ratio of the ion cyclotron frequency, ωci, to the ion-neutral collision frequency, νin. To investigate this interaction, a laser induced fluorescence (LIF) system has been developed for the Helicon-Cathode (HelCat) linear helicon plasma device at the University of New Mexico (UNM). The LIF system is based on a > 250 mW, tunable diode laser with a tuning range between 684 and 699 nm. One neutral and one ion metastable energy state can be excited. For neutral argon (ArI) LIF, the laser pumps the metastable (2P03/2)4s 2[3/2]02 level to the (2P01/2)4p 2[1/2]1 level using 696. 7352 nm light. The fluorescence radiation from decay to the (2P01/2)4s 2[1/2]00 level at 772. 6333 nm is observed. Two ion transitions are also explored, one of which yielded usable results. The system design, measurements, and analysis for axial, radial and azimuthal velocity of ArI is presented. The neutral flow is found to be axially away from the source, radially outward from the center of the machine, and azimuthally in the electron diamagnetic direction. It is less than 50 m/s in all directions. The neutral

For many decades, research work on combustion has been focused on improving combustion efficiency and reducing harmful emissions. Laser diagnostics is one of the best ways to investigate the combustion process and emission formation as it is non-intrusive and it has high spatiotemporal resolution. In this thesis work, many laser diagnostics have been developed and employed for combustion research. The laser-based optical methods cover ballistic imaging (BI), multi-scaler laser introduced fluorescence (LIF) imaging, particle imaging velocimetry (PIV), laser Doppler anemometry (LDA), and high speed LIF measurement (up to 140 kHz). Two BI systems were developed and compared, together with ultrafast shadow imaging (USI) for better imaging through a high optical depth (OD) substance, e.g. a spray. In addition, multi-scaler planar laser introduced fluorescence (PLIF) measurements were developed in Lund University Piloted Jet (LUPJ) burners including simultaneous measurement of temperature, CH radicals and OH radicals distribution, and simultaneous measurement of CH2O radicals, CH radicals and OH radicals distribution. Key parameters, such as Damköhler number, Karlovitz number, and Kolmogorov time scale, were calculated and are listed in this thesis based on LDA measurements. Moreover, high speed PLIF measurements were developed in an LUPJ burner including simultaneous OH/CH2O PLIF at 50 kHz, OH PLIF at 100 kHz and CH2O PLIF at 140 kHz, with more than 100 consecutive images for the first ever time. That was achieved by using a burst-mode laser pumped optical parametric oscillator (OPO) system synchronised with high speed cameras and high speed intensifiers. The diagnostics approaches were capable of following the temporal evolution of the reacting flow down to the Kolmogorov scale for better understanding of the transient behaviour of the eddy/flame interaction in highly turbulent premixed flames.The developed laser diagnostics have also been applied in a diesel spray in a

Biological growth has been observed on insulators installed all over the world. However, so far, its impact on insulator performance is not well known. This paper summarizes a majority of the work published in the field. Based on the gathered experiences, it can be concluded that microbiological growth is unlikely to cause severe degradation of the rubber housings of non-ceramic insulators. Furthermore, it seems that the impact of growth on the insulator performance is rather low. Techniques available for detection and characterisation of growth on insulators are also described and discusses. Among those, laser-induced fluorescence (LIF) spectroscopy has been found to give good results in remote detection of micro-organisms., QC 20141111

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Laser-induced fluorescence is a technique for optical tissue characterisation. It has a real-time capability and as the excitation light and the fluorescence emission are transmitted through optical fibres the technique is compatible to various kinds of endoscopes for hollow organ investigation. The tissue fluorescence itself with the emission from the endogenous chromophores or enhanced with exogenously administered tumour seeking agents are employed. Contrast functions are beeing developed for optimal tumour demarcation. Photodynamic therapy is a selective therapy for certain types of malignancies. In particular the topical application of a sensitising agent has been employed for human skin malignancies. Clinical examples are both from the detection and the treatment side.