Resistive strip anode

By dividing one of the signals by the sum of both, one gets the desired dependence on the position P/L. The same concept lies behind the resistive strip anode... 

Figure 4.25 Extraction of one-dimensional position information from a channelplate detector by using a continuous resistive strip anode. If an electron avalanche (shaded circular area) hits the resistive material of the anode, the charges Qt and Q2, collected on the electrical contacts (shaped rectangular areas), are proportional to the distances (P, L)...

Figure 4.26 Possible electronic circuit for deriving one-dimensional position information from a position-sensitive detector with a resistive strip anode. The two charges Q, and Q2 on the ends of the anode are amplified, shaped and converted to a digital signal. The mathematical operations of Q = Qt + Q2 and Q2/Qj are performed electronically, and the result is stored in a histogramming memory from which it is read into the computer. Q2/Q carries the information first that an electron has been detected and second at which position this electron has hit the detector. From [Wac85].

Noise from a resistive output structure is avoided in the wedge-and-strip anode. The structure is shown in Fig. 6.6. 

Attached anodes provide the particular advantage of proportionately low grounding resistance for the protection current because the actual anode body is set into both sloping sides of the plastic body as long narrow strips. The disadvantage is that the body is exposed on the ship s side and can easily be damaged mechanically. 

Anodes are not attached to the rudder but are situated between the rudder shaft and the ship s wall and connected via a copper strip. The propeller is protected via a slip ring on the shaft. To achieve a low-resistance contact, the divided copper or bronze ring has a rolled silver-bearing surface on which metal graphite brushes slide. The transmission voltage should be below 40 mV. 

Since the energy required to strip the electrons from plutonium metal at the anode is exactly matched by the energy returned at the cathode, the potential required by the process is only that required to overcome time invariant (i2r) losses in the cell circuit, and time dependent resistance (electrode polarization). 

Stripping is the most sensitive form of voltammetry. In anodic stripping polarography, analyte is concentrated into a single drop of mercury by reduction at a fixed voltage for a fixed time. The potential is then made more positive, and current is measured as analyte is reoxidized. In cyclic voltammetry, a triangular waveform is applied, and cathodic and anodic processes are observed in succession. Microelectrodes fit into small places and their low current allows them to be used in resistive, nonaqueous media. Their low capacitance... 

Almost continuous position information can be obtained from an MCP-PMT with a resistive anode or with a micromachined wedge-and-strip geometry [247, 248, 262, 312] (see also Sect. 6, page 213). The detector principles are shown in Fig. 3.11. 

A problem shared by the crossed-wire anode detector with resistor chain, the resistive-anode detector and the wedge-and-strip detector is that ratios of the pulse amplitudes have to be calculated. However, it is difficult to calculate ratios with high speed, no matter whether analog or digital calculation is being used (see Sect. 3.5, page 39). 

One important requirement is that the interfacial resistance between the anode and the concrete. However, the electrical resistance of the anode system should be proportionately lower than the combination of the interfacial resistance, the concrete cover resistance, and the steel to concrete resistance, otherwise the current will not distribute evenly to the steel. For atmospherically exposed reinforced concrete structures the anode is usually a distributed anode system , such as a paint coating on the surface, an expanded metal mesh across the surface encased in a concrete overlay, strips of anode in slots across the surface or a series of small point or discrete anodes embedded in the concrete cover or among the rebars. 

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