“Total Ionising Dose Effects on Power Amplifiers Test Analysis” project, was commenced in 1st of December 2015, and concluded succesfully in 31st of July in 2016. The project conducted with partnership of “Turkish Military Electronics Industry (ASELSAN)”. First radiation dose that power amplifiers will be exposed on a geostationary orbit were calculated. After preparations, tests were done in TAEK SANAEM Gamma Radiation Facility with a Cobalt 60 source in April 2016. The radiation doses on the components, were monitored via Alanine dosimeters during the tests.

Assoc. Prof. Dr. Bilge Demirköz, presented the results in her presentation named “Total Ionising Dose Testing of Solid State Amplifiers” ,which can be accessed online [1], at AMICSA conference in Gotenburg, Sweden. Figure 1 shows the position and alignment of the power amplifiers in a lead box during the test. Necessary RF switches were positioned in another lead box, separated from the power amplifiers by 13 meters. Their positioning during the tests can be seen in Figure 2.

Figure 1: The Lead Box with Power Amplifiers Inside

Figure 2: Position of RF Switches in Lead Box 

Measurement system for power amplifier modules prepared by ASELSAN and METU team can be seen in Figure 3. In order to measure homogenity of radiation distribution during the tests, Alanine dosimeters were used and a radiation homogenity better than 1% was measured. During the measurement, temperature was kept constant at 20º C.

Figure 3: Measurement System

Radiation tests were continued until 300 krad, and analysis results of power amplifiers and analog attenuators were given in Figures 4 and 5. No change in the output voltage of the power amplifiers were observed until 300krad. For the analog attenuator, its important to observe first attenuation value. This value oscillates as the radiation increases. Output voltage of the power amplifier and attenuation of the analog attenuation changes less than 1% with the radiation.

Figure 4: Change of GaAs Power Amplifiers Output Voltage with Radiation

Figure 5: Change of Attenuation Characteristic of the Analog Attenuators with Radiation

This project is a fine example of univeristy – industry collaboration. In future single event effects testing of electronic components developed by ASELSAN team could be done in METU-DBL.  

Figure 6: Cherenkov Radiation

Figure 7: During Test

References:

[1] R. Uzel,  M. B.Demirköz, A. Özyıldırım, O. Kalkan, H.I. Atasoy; “In-Situ Total Ionizing Dose Tests of SSPA Components”, AMICSA 2016 conference proceedings.