Summary
The Department of Low Temperature Systems (DSBT) from CEA/IRIG focus its research on technological systems over a broad range of temperature from 120 K down to few tens of milli-Kevin. The LCCS team (Cryocoolers and Space Cryogenics Lab) focus part of its work on pulse tube type cryocooler from 100 K down to 4 K. It is a cryocooler based Stirling thermodynamical cycle for which the phase shift between the pressure swing and the mass flow rate must be precisely control. It is currently actively control when reaching low temperature (< 20 K) but for reliability and complexity reason, a passive system would be preferred. The aim of this internship is to design and test such a passive system on dedicated test bench.
Full description of the subject
The Department of Low Temperature Systems (DSBT) from CEA/IRIG focus its research on technological systems over a broad range of temperature from 120 K down to few tens of milli-Kevin.
In DSBT, the LCCS team (Cryocoolers and Space Cryogenics Lab) develop small cryogenics systems from 50 K down to 50 mK with cooling power ranging from few Watts down to few micro-Watts. Among those cryocoolers, a consequent part or our work is focused on pulse tube cryocooler. Based on Stirling thermodynamical cycle, it allows to reach temperature from 4 K to 100 K with Helium gas under oscillating flow. There are being used for Earth observation (like MTG, Met-Image) at temperature around 50K. For Universe observation mission (ATHENA/X-IFU), an engineering model working at 15 K has been developed and we demonstrated 4 K on a prototype. Most of the development are performed jointly with our industrial partner Air Liquide Advanced Technologies (Sassenage).
The basic principle of pulse tube cryocoolers relies on a precise control of the phase shift between the pressure swing and the mass flow rate. To reach low temperature (< 20 K), we are currently using an active phase shift control that allows us to map the entire phase space. However, for reliability and complexity of the systems, the active control is not optimum. In the frame of a common development with Air Liquide and the DSBT, we aim at developing a passive phase shift system between the pressure swing and the mass flow rate. This implies to have a better understanding of mass flow inside the pulse tube.
First, a preliminary study shall be performed in order to propose a first design of the phase shift system as well as the preliminary test to be performed in order to better understand the phenomenon that takes place while using such a system. Then, a test campaign on a dedicated low temperature pulse tube (< 20 K) test bench will be performed in order to validate the chosen design.
Knowledge in fluid mechanics and experimental skills will be appreciated for this internship.
The internship will take place in CEA/DSBT in Grenoble.
Requested skills
Fluid mechanics, Experimental skills
Keywords
Space cryogenics, Pulse tube cryocooler
Contact
Sylvain MARTIN - Phone: 04 38 78 31 71