Abstract: A sensor for detecting the presence of thermally ionizable particles and vapors is disclosed. The sensor comprises an ionizer for supplying sufficient heat to thermally ionize the particles to be detected. The ionized particles are then caused to flow between the ionizer and an anode by impressing an electrical potential between the ionizer and the anode. The magnitude of the ion current is indicative of the concentration of the particles of vapors to be detected. The sensor is particularly useful in detecting alkali vapors and other particles, for example sodium, which may be easily thermally ionized. In most applications it is contemplated that the sensor will serve as a detector for alkali vapors and particles present in a gaseous atmosphere. Specifically it will serve as a detector for locating leaks in components of the fast breeder nuclear reactor system which employs sodium as a heat exchanger fluid.

Abstract: Variations in the conventional filament and collector electrodes of an alkali metal ionization detector, including the substitution of helical electrode configurations for either the conventional wire filament or flat plate collector; or, the substitution of a plurality of discrete filament electrodes providing an in situ capability for transferring from an operationally defective filament electrode to a previously unused filament electrode without removing the alkali metal ionization detector from the monitored environment.In particular, the helical collector arrangement which is coaxially disposed about the filament electrode, i.e. the thermal ionizer, provides an improved collection of positive ions developed by the filament electrode.

Abstract: An oxide coated filament exhibiting surface ionization and electron conductivity characteristics is employed in alkali metal ionization detectors to provide extended filament operating life.

Abstract: A system for measuring and controlling the concentration of hydrogen in liquid sodium and in gaseous environments is disclosed. The system comprises a reinforced hollow tube-like membrane which is positioned in the sodium or the gaseous environment such that the hydrogen diffuses through the membrane. Hydrogen diffusing through the membrane is removed by an ion pump to maintain a vacuum inside the membrane. The electrical current flowing through the ion pump is an indication of the hydrogen concentration. Alternatively, the hydrogen can be permitted to diffuse through the membrane until an equilibrium condition is established and a high pressure ionization gauge can be used to determine the hydrogen concentration. The membrane includes integral reinforcing sections permitting the membrane to be thin to achieve high sensitivity and withstand a high differential pressure. Valves are included which isolate the membrane from the sodium or gaseous environment so that the membrane can be easily changed.