Zapping gases with lasers to amplify and detect tiny concentrations of electric charge

After the demonstration of the laser in 1960, researchers quickly discovered that tightly focused laser pulses generated a bright spark of ionized air. The physics of this process—a laser-driven exponential growth of charge—was well-understood by the end of the 1960s. An obvious potential application was extreme sensitivity charge detection in gases through the amplification of individual free electrons, in analogy to the detection of single photons or electrons by multiplier tubes. However, various technical and physics limitations delayed this application until very recently. In this presentation we will describe the avalanche process and discuss how we overcame these limitations to develop an ultrasensitive charge detection diagnostic. Originally aired March 2022.