The JANDEL ENGINEERING LTD. Cylindrical four point probe is available in a special version for use in a high Vacuum environment.
The Hi-Vac version of the Jandel cylindrical probe head has been successfully used in vacuum that was at 1 x 10^-10m bar. The application was described in the “Journal of Physics: Condens. Matter 3 (1991) S291-S296”.
It is basically the Jandel Cylindrical Probe with certain modifications viz:
The probe head is supplied with all of the usual components except the insulating nosepiece pad is ruby, the tension adjusting screw is PTFE, and isolated terminal pins extend through the top of the probe instead of being soldered internally into brass pins. Only a tiny amount of soldering is done internally where the phosphor bronze ligaments connect into brass pins. The connection of the ligaments to the needles is done with crimps, removing the need for brazing or soldering.
Four 24″ single conductor vacuum compatible leads are connected to isolated pins using brass connectors and stainless screws as shown in the image above. Alternately, the customer can supply the lead wire of their choice. Non-anodized aluminum alloy is used for the body, nose-piece, and top, instead of the usual anodized material.
Material involved are:
- 6262 Al alloy
- Virgin PTFE
- Tungsten carbide needles
- Steel piano wire springs
- Anstenitic stainless steel screws
- Ruby (single crystal alumina) jewel guides
- Hypodermic needle tubing about dia. 1.5 mm
- Phospohor bronze connecting ligaments (to enable the needle connections to flex)
- No blind holes
The characteristics for the probe need to be defined, i.e., spring load, needle tip radii, spacing, and whether a linear or square probe pattern is preferred. It has a 1″ diameter body and is 1.9″ high (25.4mm x 48.5mm high). The probe weighs 40g.
The probe is built to high standards of quality and tight tolerances as described in the document shown here, which applies to almost all models of Jandel four point probes:
http://www.four-point-probes.com/cylindrical_app_notes.pdf
Specifications for tip radii, spacing, and planarity are verified by calibrated instruments which include video inspection systems and an optical interferometer. Loads are verified by electronic force gauge. Needles have upper and lower jeweled bearings.
The temperature rating of the Hi-Vac probe is for use at up to 120o C in an oven, however, upon request it can be built for use at up to 200o C at no additional charge.
Downloads
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Hi-Vac Probe two page brochure (59K PDF file) |
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Larger image of the Jandel Hi-Vac Cylindrical Four Point Probe Head |
Four-Point-Probes is a division of Bridge Technology. To request further information please call Bridge Technology at (480) 219-9007 or send e-mail to Joshua Bridge at: sales@bridgetec.com
