Abstract: An improved control to establish ignition timing in a spark ignited internal combustion engine near optimum efficiency without knock and/or anomalous combustion. The control operates in response to a detected ion and charged particle current in the engine exhaust and to timing pulses from the engine. When the engine is operating under steady state conditions and retarded from the point of incipient knock and/or anomalous combustion, there is very little time change in the averaged exhaust current data. When incipient knock or anomalous combustion is approached, scatter in the averaged exhaust current data significantly increases. The detected scatter in the averaged exhaust current data is used to optimize engine operation for each combustion chamber.

Abstract: Apparatus for treating a flow of material by an electric arc generates free radicals and/or atoms, and charged species, in ground or excited states. A cathode (13) and an anode (14) are arranged for striking an arc across a preferably annular gap and provide a pathway for flow of material through the gap between the cathode and anode. Each electrode has a region providing a continuous closed path for the anode spot or cathode root respectively to travel around, and means, preferably magnetic means (19), for producing movement of the arc cause the anode spot and cathode root to travel around their paths in the same sense and in substantially the same time. Preferably the paths are circular paths in parallel planes on the anode and cathode respectively, and the length of the arc remains substantially constant during travel of the anode spot and cathode root around the paths. Preferably the cathode (13) comprises a rod having a plane end face with a circumferential edge for striking the arc.