The system is designed to simulate environmental conditions of a space vehicle during the next exploration voyage to Mercury (BEPI Colombo Mission), in order to verify the behavior of antenna receiver materials. The particular requirement towards the testing system is to increase and maintain the surface temperature of a specific device under test (DUT) up to +550°C under high vacuum conditions.
The requested conditions have been reached by heating the target through infrared (IR) ceramic emitters. The IR emitters are mounted on six reflective panels placed all around the target specimen corresponding to the six faces of a parallelepiped. Each face is fixed independently to an external cylindrical structure and can be adjusted or opened in order to allow the user to access inside the test volume (Fig. 2).
Figure 2. View of the internal test volume
The specimen is suspended in the center of this parallelepiped (Fig. 3).
The cylindrical structure is made by a double layer of stainless steel reflective screens, closed on the rear side and with a removable double layer panel on the front side for the access during the test preparation. The scope of the above double layer envelope around the IR emitters parallelepiped, is to keep inside the test volume the most of the radiation produced by the IR emitters, in order to maximize the energy transferred to the target placed in the center and minimize the loss of heat in the external environment.
Figure 3. Specimen suspended inside the test volume
The above described equipment is placed inside a thermal vacuum chamber (TVC), in order to operate at the same pressure conditions of the real object (Fig. 4), that corresponds to vacuum on the order of 10-6 mbar.
During the test, with the device placed inside the thermal vacuum chamber and with its IR heating enabled, the thermal shroud of the TVC is cooled by a heat transfer fluid in order to dissipate the heat irradiated outside by the high temperature equipment, which is of a remarkable order even if it is minimized by a low emissivity coefficient of the external skin of the equipment.??? This approach allows to avoid temperature increase on the black painted shroud over values not compatible with the paint characteristics and it permits to limit the outgassing below unsuitable values for the requested vacuum level of 5 x 10-6 mbar.
The power for the IR emitters, the temperature sensors requested for the emitters surface temperature monitoring and the sensors for the DUT temperature control are brought inside the vacuum environment by dedicated feedthroughs placed on the chamber body portholes(Fig. 6).
The IR ceramic emitters can reach a surface temperature close to 1000K, which corresponds to maximum power λmax and a power emissivity of 6 Wcm-2 (Fig. 7).
Figure 7. Radiated power vs wave length
Since 1952, Angelantoni has been producing and marketing worldwide, under the ACS brand, environmental test chambers for all types of tests on materials , components and finished products. ACS has acquired a strong leadership position in the aerospace sector, the most challenging environment for simulation: after the first Space simulator in 1988 Angelantoni became one of the few leading international manufacturers at international level, and a supplier for the most important Space Research Centers testing satellites, subsystems and components.