The Low Temperature Communication Link is a component of a more ambitious programme “Smart Diagnostics of Superconducting Magnets”. The initial idea of “Smart Diagnostics” is included in the FuSuMaTech Initiative. It comes from considering a superconducting magnet as an IoT (Internet of Things) device. Even if this is presented as targeting superconducting magnets the solution is generic and can be applied to any equipment working at very low temperature. Where low temperatures are the ones in the order of the thermal shield levels, 70 K to 50 K, or below.
An equipment working under cryogenic conditions is strongly dependent in wired instrumentation for monitoring, diagnostics, control and protection.
The step forward of Smart Diagnostics is to have the instrumentation electronics confined into the low temperatures vessel with the powering and communication provided by wireless links. This presents several advantages:
a) Simplifies and gives more freedom to the mechanical and thermal design of the cryogenic vessels as we do not need inserts for the instrumentation.
b) Instrumentation gets closer to the physical source. Measurement will be more accurate, more precise and with less noise. Also opens the possibility to have more measurement points because each additional sensor does not add wires to the exterior of the vessel.
c) Instrumentation is the equipment. In the sense that the confined electronics is always easily available (once installed in the cryostat), independent of the equipment being at the factory, at the workshop, in transport or in operation. With just a Wi-Fi link, one can connect and monitor/control the equipment.
d) Data storage, monitoring, analysis and processing are decentralised and accessible via the internet.
The actual solutions for the instrumentation are based on electronics located outside of the cryogenic vessel. The diagnostic systems are connected to the few sensors at low temperature by wires which cross the different temperature layers and mechanical interfaces up to the sensing point. This is because the existent electronics are designed to work at ambient temperature and not at a low temperature.
The major challenges for Smart Diagnostics are:
– to develop a working electronic data acquisition system of high precision at a low temperature
– to develop a working wireless electronic communication link at a low temperature
– to develop a working wireless powering system at a low temperature
– to develop a radio frequency transparent material to build a “window” or an antenna, at the wall of the cryogenic vessel, for the wireless communication link and for the wireless powering system
– to develop materials and assembly technologies to build flexible PCBs (Printed Circuit Boards) for the confined electronics at a low temperature
As the challenges exceed the time and budget provided by this grant we propose to use it to work on the wireless communication link at a low temperature, in the domain of 77 K (to reduce cost because this is achievable with liquid nitrogen).
This start point will provide an essential functionality that will be used in all the subsequent steps of the development. Because the ability to transmit in real-time the data generated by a confined electronics under development is a critical requirement. Without wireless transmission, due to the confined nature, the data cannot be transmitted without complicate inserts.