Number 208 (Story #4), December 22, 1994 by Phillip F. Schewe and Ben Stein NON-NEUTRAL PLASMAS are less well studied than plasmas in which positively-charged ions and electrons intermingle. However, recent work on storing non-neutral plasmas in atom traps has shown that fairly high numbers---up to a billion same-charge particles---and lengthy storage periods---hours and days---can now be achieved. Non-neutral plasmas are of interest partly because in some cases they can remain intact longer than neutral plasmas and partly because they constitute an ideal fluid for studying turbulence. At last month's meeting of the APS plasma physics division in Minneapolis, Fred Driscoll of the University of California at San Diego reported that in a turbulent spheroidal-shaped electron plasma (electrons confined in a trap) a number of long-lived vortices formed themselves into a regular array. Eventually these vortices disappeared. Another San Diego researcher, Cliff Surko, said that he was storing positrons (up to 100 million) in his trap as a way of studying the sort of matter-antimatter interactions that occur at the heart of the Milky Way galaxy. (Science, 9 December 1994.)