Application | Deep-Space Telescope

HESS RELIES ON LAPP CABLES The twelve-fiber cable is not the only LAPP product fitted during the upgrade. A four-fiber HITRONIC ® cable conveys data for calibrating the cameras using LED lights. This happens every other night to keep down the noise of the photomultipliers that amplify the weak light signals. In addition to the four- and twelve-fiber versions, LAPP also has other models with two and eight fibers in its range, each available with common fiber types: single mode 9/125 µm OS2, multi-mode 62.5/125 µm, multi-mode 50/125 µm OM2 to OM4. On the telescope, each camera is powered via an ÖLFLEX ® CRANE cable. In addition to the dynamic fiber cables, the system does still contain some older HITRONIC ® cables with 1 GB/s. These are fixed in place and do not have to follow the movements of the telescopes. Last but not least, some cables are installed in protective SILVYN ® cable conduits. “We are very happy with the products from LAPP”, praises Jahnke. It will take a few years to see how the cables withstand the heat and dryness. But the engineer is optimistic: “We already had a handful of LAPP cables in use on the old cameras, and they have kept working brilliantly.” TRACKING CHERENKOV Cherenkov lights occur when energy-rich gamma radiation from far-away stars reaches the Earth’s atmosphere, where it generates a dim blue light for a few billionths of a second. This light hits the Earth’s surface like the cone of light from a flashlight. The five telescopes, working exclusively at night, wait for it with large mirrors for amplification and extremely sensitive cameras. Five telescopes are necessary because it allows the scientists to calculate the orientation of the light cone from the differences in time when the light hits the Earth. This makes it possible to locate the source. The hard X-rays can arise in a dying star. Gamma radiation is also a tell- tale sign of quickly rotating neutron stars known as pulsars. The HESS telescope has already discovered dozens of these objects, providing the astrophysicists with interesting clues about what is happening in the universe.

specialized HITRONIC ® cable is normally 3,000 meters, but that only 380 meters were required. Jahnke got in touch with Ecotech, a company based in Windhoek that supports automation projects in the process industry in Namibia, and which is also the exclusive supplier of LAPP products in the country. Ecotech put him in contact with LAPP Southern Africa and the LAPP product management team in Stuttgart. They made an exception and agreed to provide 500 meters of the cable especially for the project. 380 meters of this is now installed in the HESS, with the rest held in reserve. Each fiber transfers 10 gigabytes per second. The cables convey signals from the cameras to a computer in the control center. These signals include all image data and the trigger signals that synchronize all five cameras simultaneously. Data is only transferred when two or more telescopes detect Cherenkov light simultaneously, as only then is it likely to be a gamma pulse from a star. Not all fibers are used here. Only four fibers are normally used, though in some exceptional cases up to six can be utilized. The remaining fibers act as a reserve and are automatically activated in the event that one fiber fails. “Just to be on the safe side”, says Jahnke. After all, in the mountains of Namibia hours away from the capital Windhoek, there is no one who could quickly come around to install a new cable.

HITRONIC ® cable is designed for dynamic applications and can therefore be flexed continuously while in operation. When used in cable chains, speeds of up to 30 feet per second are possible; the maximum acceleration is approximately twice the acceleration of gravity. The conductors, which include secondary shielding, are about 1/32 inch (0.9 mm) thick and particularly resistant to bending. In the cable, the fibers are designed as single conductors, so each fiber has strain relief elements made of aramide fibers and a sheath of halogen-free plastic with low

LAPP cables ensure power and secure data transfer. These include HITRONIC ® HRM-FD and ÖLFLEX ® CRANE.

smoke density in the event of a fire. The advantage of this design: a connector can be directly attached to each individual cable element. The cable then contains these single conductors as well as a central element with fillers and is reinforced with aramide yarn. The outer sheath is made of PUR; it is UV-resistant, halogen-free, oil-resistant, metal-free, and highly abrasion-resistant. As a result, the cable is mechanically very robust and well suited for industrial applications with continually repetitive movement sequences, particularly in cable chains.

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