During simulations of vacuum thermal shields I have got a strange result.
Here is a simplified quasi 1D representation:
I have 4 brass plates:
1. (on the left) - set to 300K
2. (large square one) - connected to number 4
3. - floating
4. - set to 4K
Thermal exchange is set as radiation between the plates (closed system, emissivity = 1). The whole system is defined as isolated.
In the picture the 2nd brass plate got warmed (to 5.7 Kelvin) by radiation from the left, which is logical.
However, I am confused with the temperature of the 3rd brass plate - 32 Kelvin.
It seems that the hot radiation is somehow reaching the 3rd brass plate.
Do you have any suggestions why?