Spark chamber

A first spark chamber comprises a chamber having two parallel glass plates and a pair of electrodes each made of a transparent conductive film deposited on the inner surface of each respective glass plate. A second spark chamber comprises a spark chamber identical to the first with an auxiliary electrode made of a metal deposited on the opposite side of one glass plate of the chamber, and is connected to the first spark chamber to form a series circuit. A high-voltage source is connected to the series circuit through a current limiting resistor and the auxiliary electrode is wired through a resistor with one electrode of the first chamber to form a potential difference between the auxiliary electrode and the opposite electrode of the second chamber. It has been proven that a spark column with a small diameter occurs uniformly over the electrode surface with a high sensitivity. (Ohno, Y.)