Control of plasmas for production of ultraslow antiproton beams

To produce ultraslow antiproton beams, decelerated antiprotons were captured in an electro‐magnetic trap and cooled by collisions with preloaded electrons. This electron cooling feature was nondestructively monitored by measurement of electrostatic oscillations of the confined electron plasma. The radial distribution of the plasma was controlled for efficient cooling and extraction by utilizing rotating wall field technique.