Glossary
Additional background information and descriptions of all available product options.
JPE positioners are available in 3 grades of vacuum compatibility. Independent of the selected grade, assembly of JPE positioners is done in a cleanroom environment, the design rules for vacuum engineering are followed and vacuum compatible materials are used. In their default supply condition positioners are compatible with the 1E-5 mbar regime, but can be upgraded to HV and UHV compatibility. Some systems cannot be delivered in the UHV grade (yet).
HV upgrade
Positioners are compatible with a 1E-8 mbar vacuum. Prior to assembly each part is professionally cleaned for vacuum compatibility according standardized industrial processes. This ensures that after assembly no high outgassing contaminants are trapped between surfaces, which could manifest itself as an apparent “leak” over a long period of time.
UHV upgrade
On top of the HV upgrade additional cleaning steps may be required, in some occasions materials with lower outgassing properties are used and the positioners can be baked to 150 degC. Compatibility with a vacuum in the order of 5E-11 mbar or lower is achievable, requiring prolonged vacuum baking.
RLS (Resistive Linear Sensor)
The RLS (Resistive Linear Sensor) is a resistive based sensor that can be added to selected positioners for position feedback. A wiper slides over a resistive track and the measured voltage is a measure of position. Resolution is determined by electrical noise and length of the resistive track. It is an absolute sensor, which means that it will give the actual position, even after recovering from a power shutdown. The RLS requires the RSM electronics module as voltage source and position readout.
COE (Cryogenic Optical Encoder)
The COE (Cryogenic Optical Encoder) is a fiber based optical encoder that can be added to selected positioners for position feedback. It works by illuminating a grid and detecting high/low intensity transitions from features in the grid. Resolution is determined by the pitch of these features. It is an incremental encoder, which means that it will reset to “zero” at a power shutdown. The COE requires the OEM electronics module as light source and position readout.
Power dissipation in stick-slip based cryogenic positioners is of importance as it can cause the experiment to heat up during use. Many ways of representing this power dissipation can be used and it is very easy to draw the wrong conclusions.
This application note distinguishes the contribution of several dissipation sources; piezo, friction and cable loss and compares these for 3 types of piezo; 150 V linear stack, 60 V linear stack and 500 V shear piezo. Benchmark dissipation values are determined based on a stick slip positioner driven with a sawtooth signal.