Gallery: Cool instruments at the 2015 International Microwave Symposium

Eliminating standard spark plugs with microwaves

One of the more interesting demonstrations was that involving microwaves adopted to enhance the plasma generated by an automotive spark plug. A standard ignition spark is characterized by high voltage with peak current not exceeding 200 mA. To boost fuel economy and further reduce emissions, automotive designers would like to get a hotter spark. They can do that by using microwaves to generate an RF plasma in the combustion chamber. Concealed safely behind a mesh screen (bottom right) at the NXP Semiconductor booth was a version of a spark plug that used RF to create a high-energy plasma with a very high energy output several hundred times greater than that of a conventional spark. The high energy photonic energy of the plasma spark significantly reduces CO, NO and NOx emissions while also letting automakers use a much leaner air/fuel mixture, so lean that it wouldn’t ignite with conventional spark plugs. At the NXP booth, the company used one of its instruments (bottom left) to drive the RF plug and read out its RF impedance (Smith chart display, top) through a directional coupler. The plug is significantly smaller than an ordinary spark plug. Designs employing the idea could deploy in about four years, NXP said.
NEXT PAGE: Test suites make modular