Abstract: Apparatus for the physical vapor deposition of an alloy whose constituent ements have widely differing vapor pressures comprises an inner evaporation crucible (1) surrounded by a second evaporation crucible (2) having an array of nozzles (9) angled towards collector (5). In use of the apparatus, a charge (3) of relatively low volatility is evaporated from inner crucible (1) using an electron beam (7) focussed by magnet (8). Charge (4) in second crucible (2) is of much higher volatility and is evaporated by radiant heating. The nozzles (9) direct the vapor from charge (4) along pathways which intersect the vapor rising from charge (3) such that the combined vapor stream reaching collector (5) is an intimate mixture of constituents. The nozzles (9) may also serve to control the flow rate of vapor from the second crucible (2).

Abstract: A method of, and system for, spraying is provided in which voltages generated by the passage of pressurized medium through a spray nozzle is monitored. The generated voltage has characteristic patterns. Monitoring the variations in these patterns or the exceeding of predetermined voltage limits enable close control to be monitored over the spraying operation and for remedial action to be taken in due time.

Abstract: A leak detector has a gas probe 1 for sensing signal gas escaping from an enclosure containing that gas at a pressure slightly in excess of ambient surrounded by a curtain of barrier gas. The reading of a gas analyzer such as a mass spectrometer depends on the height of the probe from the surface. A height sensor is attached to the leak detector and a programmable amplifier 6 contains information on the characteristic curve of the gas sensor. An output signal from the programmable amplifier compensates for the height of the probe from the surface being detected. The speed of the leak detector can be corrected for in the same way.

Abstract: A leak detector comprises a detector head which is to be scanned across a surface to detect a signal gas eminating from the surface. The opposite side of the surface from the head is supplied with a signal gas under pressure so that signal gas passes through leaks in the surface. Detection of signal gas by the head should then constitute detection of a leak. A curtain 1 of barrier gas is provided around a sample inlet 2 to protect the inlet from spurious signal gas. Orifices 36 provide narrow high velocity jets 38 which impinge on the surface S within curtain 1 and break up jets such as 34 of signal gas which escape under the curtain 1 without allowing the signal gas to reach the sample inlet.