New design concept for ion sources

Vacuum News mechanical interlock maintains the latch, even with the coil de-energized, so that the spring is not discharged unnecessarily. With remote lamps fed via the fail-safe reset switch, the control centre is automatically alerted to spring discharge on power failure. The actuator is inoperable until the spring is reset, when indication is restored. The spring reset knob replaces the position indicator and manual operator of the basic 010, and indicates only whether or not the spring is set (ON) or discharged (OFF). An optional refinement in the fail-safe mode is the provision for deliberate tripping of the spring latch by battery or other dc source. A dc latch coil is substituted for the standard ac unit; the spring charge is then retained-even on power failure-until such time as the controller chooses to trip it by disconnection.

A microforce

balance

The ROBAL control unit provides two visual digital ranges and an output which permits any range to be selected. It may be used with a balance head mounted in a standard weighing compartment or in a vacuum enclosure. A choice of two weighing head capacities is offered: (1) 100 mg, with capacity of 1 g (2) 200 mg, with capacity of 5 g. The visual ranges provide sensitivities of: 0.01 mg up to 100 mg with 1 g capacity head, 0.001 mg up to 25 mg, 0.01 mg up to 200 mg, 0.001 mg up to 50 mg with 5 g capacity head. In each case the recorder full scale can be set to any sensitivity within the entire range covered by the head in use. The instrument is in two parts : a weighing compartment containing the balance head and the microprocessor control cabinet. A multi-way cable connects the balance head to a socket at the rear of the control cabinet. The balance beam is made of aluminium and gold-flashed berylium copper in a strong but light cantilever construction. Light-weight pans, pan carriers and calibrating weights are provided. At the rear of the control cabinet are sockets for a mains cable (200/240 V 50 Hz) and for an output for use with a 10 mV pen recorder. Where the Time Derivative Facility has been ordered, an additional socket is provided for output to the second pen of a 10 mV recorder. The weighing head can be mounted either in a weighing compartment or a glass vacuum bottle. The following controls and displays are mounted on the front panel : ON/OFF pushbutton switch; Range Selector pushbutton switch (xl0 sensitivity) ; Calibration Potentiometer (CAL) for each of the two ranges; Three Digital Tare pushbuttons (negative (TARE), slow (S) and fast (F). Pushbutton for setting recorder range (R) ; Pushbutton for setting recorder expansions (E). Full scale deflection (FSD) on the recorder is always EXP display multiplied by the RANGE display; sample weight display in milligrams (WEIGHT MILLIGRAMS) ; recorder full-scale range display (RANGE) ; recorder expansion display (EXP) ; recorder span display (SPAN) ; head selection switch (for selecting standard or CT5 weighing head). C I Electronics Ltd, Brunel Road, Churchfields, Salisbury, Wilts, UK

‘Ternpatch’ temperature

thermometer measuring

strips-a aid from

versatile Comark

‘Tempatch’thermometer strips offer convenient means of monitoring temperature. The ‘Ternpatch’ strip takes the form of a label, measuring 50 x 20 mm, sensitive to a particular temperature span, each range being split into eight segments. Upon exposure to an elevated temperature the segments change from silver-grey to black when their individual temperature characteristic is reached. Labels are self-adhesive, easily fixed to clean grease-free surfaces with light finger pressure. Encapsulation of the sensitive area is such that it is impervious to oil, water and steam. ‘Ternpatch’ thermometer strips are available in five standard ranges; (A) 37-65’C. (B) 71-110°C. (C) 116-154°C. (0) 160-199°C and

‘Ternpatch’ thermometer strips from Comark Electronics Ltd. Five standard ranges are available. Each pack contains ten strips of chosen range.

(E) 204-26O’C. Accuracy is claimed to be plus or minus 1%. Each pack contains ten strips of whichever range specified. Comark Electronics Ltd, Brookside Avenue, Rustington, Sussex BN16 3LF. UK

New

design

concept

for

ion sources

A new concept in ion source design for providing very stable, high intensity beams of metallic ions which is also compatible with ultra high vacuum installations is now available from Dubilier Scientific Ltd. Developed in partnership with the UKAEA Culham Laboratory the system, which comprises a source of liquid gallium and a stabilized high voltage control unit, is simple to install and operate, and will provide a stable source of gallium ions at currents ranging from 5 to 100 PA and at energies from 0.1 to 10 keV. The source comes as a compact unit mounted on a standard 70 mm standard uhv flange. The control unit is mounted on a standard 19 in. rack with handles and mounting slots. Designed specifically for ion source applications it provides multiple outputs which can be controlled either manually or via feedback systems according to a desired pattern. Metering of all key values is provided. The ‘Culham’ system, which is patented, should find application in a wide range of research and development fields from atomic physics and materials analysis, to ion implantation. Dubilier, Chaucer Trading Estate, Launton Road, Bicester, Oxon, OX6 OTU9, UK

Recent

papers

describing

(1) Intense field-emission Technol. 12 (1975).

the

Culham

ion source

ion source of liquid metals. J. Vat. Sci.

(2) Miniature ion sources for analytical instruments. Nucl. lnstrum. Meth. 149 (1978). 3rd Int. Conf. on Ion Beam Analyses, Washington, D.C. (3) Molten metal field ion sources. Inst. Phys. Conf. Ser. No. 38 (i 978).