Hi Guest! Forum rules have been updated. All users please read here.

Reply to thread

Message: <blockquote data-quote="tequilashooter" data-source="post: 432218" data-attributes="member: 27144"><a href="https://www.adelaide.edu.au/ipas/our-research/defence-security/cryogenic-sapphire-oscillator-the-sapphire-clock#defence-applications">Cryogenic Sapphire Oscillator - 'The Sapphire Clock' | Institute for Photonics and Advanced Sensing | University of Adelaide</a>The culmination of 20 years of leading-edge fundamental research, combined with cutting-edge engineering, has led to a disruptive technology that is now revolutionizing a vital Australian defence asset. The Sapphire Clock offers a 1000-fold improvement in timing precision, which delivers an improved capability for Australian Defence to identify threats to Australia using the Jindalee Over-The-Horizon Radar Network.The Cryogenic Sapphire Oscillator has a 5 cm cylinder-shaped sapphire crystal that is cooled to about -267 °C, or about 5 or 6 degrees above absolute zero. At this temperature, the microwave energy lost in the sapphire crystal is the lowest of any substance on Earth. Microwave radiation is injected into the sapphire crystal and propagates around the circumference of the crystal (just inside the surface). The way the microwave radiation moves around the crystal is called a “Whispering Gallery”. Lord Rayleigh first discovered this concept in 1878 when he could hear someone whispering far away on the other side of the church dome at St Paul’s Cathedral.There is one particular frequency that will excite the natural resonance of the sapphire crystal – this corresponds to the signal that reinforces itself after one round trip around the crystal surface. A good analogy might be to imagine hitting a bell and using its regular oscillations to count time.  The losses in sapphire are so low that if it were a conventional bell then it would keep ringing for millions of years. However, in the sapphire crystal the resonant frequency is so high—10 billion cycles per second—that the electromagnetic signal rings only for a hundred milliseconds."Heard that KRET was also designing an airborne photonic crystal which I do not know if it was sapphire as well. But I guess it makes sense why that company has interests in cryogenic cooling <a href="https://www.kret.com/media/news/kret-provel-kruglyy-stol-posvyashchennyy-kontseptsii-razvitiya-tekhnologiy-krioelektroniki/">КРЭТ провел «круглый стол», посвященный концепции развития технологий криоэлектроники (kret.com)</a>"Within the framework of the meeting, industry experts reviewed the report "On the concept of development of cryoelectronics technologies", discussed the conditions for improving electric propulsion systems for air and sea transport, the state and prospects for the development of the production of electronic component base and converter technology with cryogenic cooling.Representatives of enterprises - end users of the products being developed took part in the meeting. They stressed their readiness to take part in the testing of experimental samples.Nikolay Kolesov, General Director of KRET JSC, Chairman of the Novgorod and Mariysk branches of the Union of Mechanical Engineers of Russia, emphasized the importance of the work of industry expert platforms that allow specialized experts to exchange experience, substantively consider key issues of their work, and jointly develop an optimal development strategy."</blockquote>

Verification: What year did the first man go to space? (answer has 4 numbers)