Improved OCXO's oven using active thermal insulation

摘要

This paper shows how it is possible to improve the performance ofnthermal enclosures by using a compensating system the principle of whichnhas been described by F. Walls a few years ago (41st AFCS, 1987). It isnshown that because of the thermal network between the outsidentemperature, the temperature sensor and the device to be regulated, thenlatter may undergo residual temperature variations which reduce thenoverall thermal efficiency of the oven. This paper shows how thermalntransfer functions can be measured by using an experimental setup innwhich the node temperatures are measured by thermal sensors. Bynidentifying the thermal response of the nodes with the theoreticalntransfer function under external temperature or heater excitation, thencomponents of the equivalent R-C network can be determined. By knowingnthese thermal transfer functions, it is then possible to make use of ancompensating system which can eliminate the parasitic static as well asndynamic thermal effects. Validating measurements and experimentalnresults are presented which show the strong improvement achieved by thisncompensating system with respect to the conventional approach