Current spikes

In Fig. 5.2(f) (the highest stress) an early time current spike is apparent. Other records show this behavior more clearly. The impact-time spike shows... 

Platinised Ti, Ta or Nb < 1000 Am/m (consumption) Discontinuities in Pt coat protected by oxide film on subtrate sensitive (< lOOHz) a.c. ripple in d.c. or negative current spikes causing electrode consumption maximum operating potential with Ti substrate 9 V... 

The control experiment in pure supporting electrolyte (dotted lines in Fig. 13.2) shows a sharp faradaic current spike, which is mainly due to pseudocapacitive contributions (adsorption of (bi)sulfate and rearrangement of the double layer) plus oxidation of adsorbed Hupd (dotted lines in Fig. 13.2a), but no measurable increase in the CO2 partial pressure (m/z = 44 current) above the background level (dotted lines in Fig. 13.2b). Therefore, a measurable adsorption of trace impurities from the base electrolyte can be ruled out on the time scale of our experiments. Moreover, this experiment also demonstrates the advantage of mass spectrometric transient measurements compared with faradaic current measurements, since the initial reaction signal is not obscured by pseudocapacitive effects and the related faradaic current spike. 

Figure 3-8 Ways to Reduce the Reverse Current Spike in Fligh-voltage Boost Regulators...

Reverse recovery shoot-through current spike through Q1 occurs if during the preceding td (deadtime) interval the freewheeling current prefers to go through the body diode of Q2 instead of the paralleled Schottky... 

The abrupt transition to the 6,7 orientation manifests itself in cyclic voltammetry as a sharp current spike (Figure 6). The cathodic spike was found to contain a charge of 2.9 fiC cm, while its anodic counterpart contained 3.3 pC cm". The peak separation was 100 mV this large value is due to the large iR losses suffered in the thin layer cell. 

Figure 7.6. Part of a current-time record during a mononuclear layer-by-layer growth of a quasiperfect Ag( 100) crystal face with a circular form in the standard system Ag(100)/6 MAgN03 at T7 = -6 mV and T = 318 K. Surface area A = 3 X 10 cm . Current density i = 1 mA/cm. The current spikes indicate the formation, growth, and decay of new layers. (From Ref. 34, with permission from the Electrochemical Society.)...

In this section, we have described a demonstration of an all-SiC dc-ac inverter (using SiC power switches and SiC diodes) operated in excess of 400W and at case temperatures of approximately 150°C. Two factors related to the system s implementation limited the operational power levels of this circuit. First, load instability caused excessive current spikes and GTO failures and was corrected using a closed-... 

Figure 6.24. (a) Cyclic voltammogram of electro-oxidation of formic acid on a Pt(100) single-crystal showing current spikes indicating sustained current oscillations and (b) current oscillations measured at various fixed potentials all potentials are with reference to the Standard Calomel Reference Electrode (SCE) (adapted from [140]). 

Current spikes that are attributable to rapid adsorption or desorption of an adsorbate are sometimes observable for strongly adsorbing but electroinactive species such as camphor at a mercury electrode. The spike is a nonfaradaic current caused by the change in capacitance resulting from the sudden alteration in double-layer structure when the molecule adsorbs or desorbs. 

A fault current-limiter is a component which protects power transmission and distribution systems from surges caused by, for example, a lightning strike, fulfilling a function similar to that of a varistor (see Section 4.3.1). The limiter should be capable of reducing the fault current to a fraction of its peak value in less than a cycle. Because for this application the requirement is for low Jc, fault current limiters are already a commercial product. In the case of the lead shown in Fig. 4.58(b) the fault current is limited to a safe value within 5 ms of the arrival of the current spike . 

Figure 25 Current versus time behavior for Type 302 stainless steel in 1,000 ppm NaCl at (a) a potential between its repassivation and breakdown potentials, and (b) at a potential below its repassivation potential. Note the existence of an incubation time before stable localized corrosion occurs in (a). The small, short-lived current spikes during the first 400 s are due to the formation and repassivation of metastable pits, which can also be observed in (b), although they are of a smaller magnitude.

That is, adsorption of Br at Pt surfaces is a redox process. The reverse of eqn. (13), reductive desorption of Br as Br anions, occurs at potentials more negative than - 0.1 V vs. the Ag/AgCl (1M KC1) reference). The onset of Br desorption during a negative-going potential scan was signaled by a sharp, pH-independent current spike due to a structural transition within the Br layer. 

Figure 5.9 Part of a current-time record during deposition of silver in the standard Ag (100)/AgN03 system [5.20]. Overvolt e rj =-6 mV. The current spikes indicate the formation, growth, and decay of new layers.

---