# Implementation of a Cryogenic Facility for Space Debris Analysis
## 3 Prototype Design
### Material Selection  
The main criteria for material selection were thermal properties (i.e., thermal conductivity) and material costs.  
Using a material with high thermal conductivity allows a heat flux higher than when using a material with low thermal conductivity. The following materials were selected to implement the instrument setup:  
* Aluminum  
Aluminum alloy 5083 is known for its exceptional performance in extreme environments. This alloy is a lightweight, strain-hardened, corrosion-resistant, and high-strength material that is commonly used in high-strain-rate applications such as those experienced under shock loading [10]. The properties of aluminum 5083 at 25 \({}^{\circ}\)C are shown in Table 1.  
The variation in the thermal conductivity and linear expansion of aluminum 5083 [11] is shown in Figure 2.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Physical Property** & **Value** \\ \hline Density & 2660 kg/m\({}^{3}\) \\ Tensile strength & 290 MPa \\ Elastic modulus & 70 GPa \\ Thermal expansion & \(24\times 10^{-6}\)/K \\ Thermal conductivity & 121 W/m K \\ Specific heat & 900 kJ/kg K \\ \hline \hline \end{tabular}
\end{table}
Table 1: Properties of aluminum 5083 at 25 \({}^{\circ}\)C.  
Figure 2: Variation in the thermal conductivity and linear expansion of aluminum 5083 [11].  
* Stainless steel  
Austenitic stainless steels are the most common choice for high-vacuum and ultra-high-vacuum systems. Stainless steel 304 is a typical choice, and properties of stainless steel at 25 \({}^{\circ}\)C are shown in Table 2.  
The variation in the thermal conductivity and linear expansion of stainless steel 304 [11] is shown in Figure 3.  
* Copper  
Oxygen-free high-thermal-conductivity (OFHC) copper with high purity, 99.99%, is widely used in cryogenics. It is a good heat exchanger due to its good thermal conductivity and is used in the system's thermal straps and where they are attached, namely the cold finger and pistons. The properties of copper at 25 \({}^{\circ}\)C are shown in Table 3.  
* Epoxy  
ISOVAL FR4-HF is a halogen-free epoxy glass laminate with a limiting temperature of 180 \({}^{\circ}\)C. Epoxy glass laminates are even usable for cryogenic applications at temperatures  
\begin{table}
\begin{tabular}{c c} \hline
**Physical Property** & **Value** \\ \hline Density & 8000 kg/m\({}^{3}\) \\ Tensile strength & 517 MPa \\ Elastic modulus & 190 GPa \\ Thermal expansion & \(18\times 10^{-6}\)/K \\ Thermal conductivity & 16 W/m K \\ Specific heat & 500 kJ/kg K \\ \hline \end{tabular}
\end{table}
Table 2: Properties of stainless steel at 25 \({}^{\circ}\)C.  
Figure 3: Variation in the thermal conductivity and linear expansion of stainless steel 304 [11].  
\begin{table}
\begin{tabular}{c c} \hline
**Physical Property** & **Value** \\ \hline Density & 8900 kg/m\({}^{3}\) \\ Tensile strength & 395 MPa \\ Elastic modulus & 110 GPa \\ Thermal expansion & \(24\times 10^{-6}\)/K \\ Thermal conductivity & 390 W/m K \\ Specific heat & 900 kJ/kg K \\ \hline \end{tabular}
\end{table}
Table 3: Properties of copper at 25 \({}^{\circ}\)C.  
close to absolute zero. These laminates have increased mechanical strength and a modulus of elasticity can be observed, but at very low temperatures, for example, in liquid nitrogen or liquid helium, they do not show vitreous embrittlement like rubber or thermoplastics.  
The properties of the ISOVAL FR4-HF epoxy at 25 \({}^{\circ}\)C are shown in Table 4.  
The variation in the thermal conductivity of the ISOVAL epoxy [12] is shown in Figure 4.