Ultracold Plasmas

Plasma exists in the universe throughout an amazing range of parameters, from temperatures of 15 million Kelvin in the core of the sun to 200K in the ionosphere and densities of 1030 cm-3 in a white dwarf to 1 particle per cm3 in interstellar space. Using techniques of laser cooling, temperatures of neutral plasmas have now been  lowered to below one Kelvin.  By photoionizing a sample of laser-cooled atoms with light tuned just above the ionization threshold, ultracold neutral plasmas can be formed.  Our group created the first ultracold plasmas in 1999 at NIST, and have continued to study a wide range of properties such as plasma expansion including the effects of magnetic fields, collective modes and instabilities, and recombination into Rydberg atoms.