Speaker
Description
The goal of this project is to demonstrate a miniature Timing Source (mTS) with low power consumption and frequency drift at least one order of magnitude better than more bulky Oven Controlled X-tal Oscillators (OCXO). The latters are currently considered the best available option in Space for timekeeping applications. The mTS technology is based on Orolia’s commercial rubidium clock adapted for low power and volume. For example, the power demanding rubidium plasma-lamp has been replaced with a low power VCSEL (Vertical Cavity Surface Emitting Laser). In addition, the size of the glass-blown rubidium vapor cell has been reduced to fit the complete physics package inside a commercial DIL-14 hermetic package. The complete mTS clock is shown in the picture below. The clock volume is 51x51x18 mm3 with a maximum (worst case) power consumption of 500 mW in cold conditions.
For space usage evaluation, the mTS clock has been tested in vacuum for a period of 3 months. The measured short-term frequency stability is shown in the graph below, together with the project specifications (green line). In addition, the measured long-term drift of 2E-12/day is within the specified requirement. Besides vacuum testing, the mTS clock has been submitted to radiation tests, taking advantage of the Co-60 facility at ESTEC. The radiation test showed that the physic package is insensitive (within retrace error) up to 100 kRAD of Total Ionizing Dose (TID). Work is still needed to reduce the thermal and magnetic sensitivity of the mTS clock down to the target values.
| ESA Technical Officer | Marco Belloni |
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