Diode system

Olesberg JT, Arnold MA, Mermelstein C, Schmitz J, Wagner J. Tunable laser diode system for noninvasive blood glucose measurements. Applied Spectroscopy 2005, 59, 1480-1484. 

Figure 3.4 The structure of the glow discharge in a DC diode system.

All of the above films have typically been deposited using RF capacitively-coupled parallel plate (diode) systems. Lately, high density plasmas with gas injection downstream of the main plasma are being introduced. To deposit oxide in such a system, for example, one would feed oxygen through the plasma and SiH4 downstream (see Fig. 20) some distance above the substrate. Many other kinds of films have been deposited by PECVD. An example is diamond films [239]. 

The laser in FT-Raman spectrometers (Fig. 4.5) is the continuous wave Nd " /YAG system operating at 1064 nm with output power up to 2000 mW. The laser is optically pumped by either a lamp or diode system. In both cases, nonlasing hnes are generated. They have to be removed by very effective notch filters (NF), otherwise they get mixed up with the Raman spectrum producing so-called laser line artifacts. 

F%. 13a-d. Dq>o ition airagemeiits a. plane-paralld date electrode (rf diode) system plaana potymerizatiem with metal co-sputteiing or evaporation, b. plane-paraUe) date dectrode (rf diode) system with a metal co-evaporaticm for composite dasina polymers (bottom electrode) or a-C H films (top excitation electrode). c. inductive excitation of a monomer or monomer/argon mixture and metal co-evaporation, plasma zone outside-coil full line plasma zone around substrate-coil dashed line. d. plane-parallel mesh electrode system with metal co-evaporation. 

Roy et al. [123], using an ordinary rf diode system, sputtered in aigon (1 Pa pressure) PTFE/Pt-10% Rh, Au, Cu, and Hconol/Pt-10% Rh, Au targets. Ekonol (trade name of Carborundum Co) is an aromatic polyester based on /7-hydroxybenzoic acid. 

In the case of rectifying elements, the total installed cost of a thyristor system is usually less than that of one based on diodes. Operating costs also are lower. Maintenance costs, as we saw in Section 8.3.1.2B, are lower because of the use of static, solid-state control devices rather than the mechanical switchgear of a tap changer. Rectification efficiency might be expected to suffer from the loss of part of the sine wave before firing, but this loss usually is comparable to the inefficiencies of the regulating transformers and the saturable reactors in a diode system. 

The distortion of the output waveform in a thyristor-based system is therefore at least as great as the distortion caused by a diode system. Fortimately, the reactive power compensation that accompanies most large rectifier installations also tends to absorb some of the harmonics. Configuring the added capacitance as a harmonic filter therefore offsets some of the loss. 

Figure 4.14 Schematic representation of the light-gated nanofluidic diode system at different pH values.

Pump-probe experiments in the pico- and subpicosecond range were performed via tunable femtosecond pulses in the near infrared generated from an amplified continuum as described elsewhere [9,10]. The excitation energy was adjusted so that no more than 20% of the reaction centers were excited by each pump pulse. Transient absorption kinetics were recorded at a given wavelength using a two-diode system at the output slit of a spectrometer. 

This can give rise to extensive heating of surfaces in the dc diode system. In the dc diode discharge configuration, the plasma-generation region is primarily near the cathode however, the plasma fills the contained volume. This plasma can be used as a source of ions for bombardment, or for activation of reactive species. 

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