Piezoelectric spark

All methods of plasma production require some electrons to be present as electric-discharge initiators. For a plasma torch, the initiating electrons are introduced from a piezoelectric spark directed into argon gas flowing in the interval between two concentric quartz tubes. 

Fig. 6.21 (a) A piezoelectric spark generator, (b) A piezoceramic cylinder under axial... 

Narrow-necked polythene bottles (50 or 100-mL), piezoelectric spark generator, sparking plug attached to base plate, gas inlet tubes, 1-L beaker, dropping pipette, measuring cylinder, safety glasses, protective gloves. 

By use of a piezoelectric device, as in a gas lighter, a small spark containing electrons and ions can be produced. If the spark is introduced into the gas in a discharge tube, it will provide the extra initial electrons and ions needed to start a continuous discharge. A plasma torch is frequently lit (started) in this fashion. 

These two anciently served as a means of ignition. They still can. Although the sparking of flint and steel is strictly a mechanical phenomenon, any subsequent fires will not be. Other forms of silica still serve as igniters to this day, via the piezoelectric effect. 

Thin sheets of piezoelectric materials are used in sensors, buzzers, and actuators. In addition to the conventional vibrators, pressure and acceleration sensors are now also being manufactured from these materials. Lead zirconate titanate (PZT) is one of the most common materials used for these applications. The trend is to produce thinner and thinner and smaller and smaller parts. Therefore tape casting has become the manufacturing route of choice. One of the basic applications of piezoelectric ceramics is as a gas igniter where a spark is generated by the piezoelectric under an applied mechanical stress. Microphone discs are also prepared from thin... 

One of the very basic applications of piezoelectric ceramics is a gas igniter. The very high voltage generated in a piezoelectric ceramic under applied mechanical stress can cause sparking and ignite the gas (Fig. 4.1.5). There are two means to apply the mechanical force, either by a rapid, pulsed application or by a more gradual, continuous increase. 

Piezoelectric cavity pressure sensors are suitable for direct use in the cavity due to their physical properties. They are usually installed flush with the mold wall and can be adjusted to the surface by spark erosion or grinding of the sensor front. If installed correctly while maintaining the required drilling tolerances, an error-free measurement of the cavity pressure can be assumed. 

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