Free-Floating Atmospheric Pressure Ball Plasmas

Ball plasmas were created in a laboratory, using an electric arc discharge (4-250 A at up to 5 kV) from points of metal onto a water surface. The rising plasmas were studied with still and video cameras, photodiodes, power meters, and spectroscopy. The plasma consists of positive salts from the solution and center electrode material, and negative hydroxyl radicals. Various salts (CuSO
₄
, CuCl
₂
, NaCl, LiCl, and CaCl
₂
) and copper or aluminum center cathode materials were tried. The color is characteristic of the metal from solution. While observing with an Ocean Optics USB 2000 spectrometer, it was confirmed that the material in the cooling (~0.3-eV) plasma, comes from the water and not the surrounding air.