Abstract
We experimentally and theoretically investigated the effects of ionizing radiation on a stack of graphene sheets separated by polymethyl methacrylate (PMMA) slabs. The exceptional absorption ability of such a heterostructure in the THz range makes it promising for use in a graphene-based THz bolometer to be deployed in space. A hydrogen/carbon ion beam was used to simulate the action of protons and secondary ions on the device. We showed that the graphene sheets remain intact after irradiation with an intense 290 keV ion beam at the density of 1.5 × 10 cm. However, the THz absorption ability of the graphene/PMMA multilayer can be substantially suppressed due to heating damage of the topmost PMMA slabs produced by carbon ions. By contrast, protons do not have this negative effect due to their much longer mean free pass in PMMA. Since the particles’ flux at the geostationary orbit is significantly lower than that used in our experiments, we conclude that it cannot cause tangible damage of the graphene/PMMA based THz absorber. Our numerical simulations reveal that, at the geostationary orbit, the damaging of the graphene/PMMA multilayer due to the ions bombardment is sufficiently lower to affect the performance of the graphene/PMMA multilayer, the main working element of the THz bolometer, which remains unchanged for more than ten years.
Highlights
THz fingerprints of space objects carry information of tremendous importance enabling insight into the past and future of the Universe
By using hydrogen/carbon ion beam we study experimentally the performance of the graphene/polymethyl methacrylate (PMMA) multi-stacks comprising one, three and five graphene/PMMA bi-layers placed onto the fused silica substrate
The dependence of the THz transmittance and Raman spectra on the radiation dose demonstrates that the irradiation with a beam comprising 30% of hydrogen and 70% of carbon ions having the energy of 290 keV at a density of 1.5 × 1012 cm−2 due to extensive heating that results in the PMMA spacer melting and formation of the bubbles between graphene/PMMA structures leads to the evaporation of the topmost graphene/PMMA
Summary
THz fingerprints of space objects carry information of tremendous importance enabling insight into the past and future of the Universe (see [1] and refs therein). Detection of the ultra-weak THz signals currently relies on bolometers [8,9,10,11,12] that convert the electromagnetic energy into heat due to the Joule effect. THz bolometers for space telescopes require materials combining high THz absorption ability, tunability of the detection wavelength in a wide range and high resistance of the bolometer to ionizing radiation. Makes this material very attractive for use in the THz bolometers. It has been shown both numerically [16,17] and experimentall [18,19,20] that graphene is highly resistant to ionizing radiation because the one-atom thick graphene sheet is hardly visible for high energy ionizing particles.
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