Plasma-Based Device for Mechanical to Electrical Energy Conversion

Transient spark discharges are plasmas that can be used for a variety of applications, including pollutant removal, water treatment and others. Existing systems require high voltage power supplies to create the spark, which limits their use in the field.

Jaenicke et al report the development of a simple device based on a piezoelectric crystal that can generate transient spark discharges using a hand-operated crank. The piezoelectric crystal, a lead zirconate titanate ceramic, PZT, is used in commercial gas grill igniters and forms the basis of the group’s device.

The investigators designed a hand crank that used a drive shaped like a snail’s shell to generate a series of sparks. The crank repeatedly compresses a spring-loaded firing mechanism that forcefully impacts the PZT crystal, creating a charge polarization. The two ends of the crystal develop high voltages of opposite polarity.

With each rotation of the crank, transient sparks form from two electrodes connected to the ends of the crystal. The group measured changes in voltage and current for each electrode over time.

The PZT crystal returns to equilibrium quickly, and consistent behavior was observed over multiple discharges. “The electrical behavior of the discharge was nearly the same as from a high voltage power supply,” said author David Go.

Although the system is relatively inefficient, since less than 2% of the spring’s mechanical energy is converted into plasma energy, these results show promise. “In principle, this device could be actuated as fast as 125 kHz and still operate successfully,” Go said.

The authors suggest this type of device could be embedded in an internal combustion engine, harvesting mechanical motion or vibrations to create a plasma-based pollution mitigation system.

Source: “Hand-generated piezoelectric mechanical-to-electrical energy conversion plasma,” by Olivia K. Jaenicke, Federico G. Hita Martinez, Jinyu Yang, Seong-kyun Im, and David B. Go, Applied Physics Letters (2020) The article can be accessed at https://doi.org/10.1063/5.0018967 .