(The news is from China News Internet given by reporter Xiaoying Zhu on April 27th.)

The world's largest vacuum solar telescope which has been captured the huge sunspots of solar “face" this month will be upgraded. It will be pasted power "cooling paste" like "mask". On April 27th, the reporter Xiaoying Zhu interviewed Professor Bozhong Gu of Nanjing Institute of Astronomical Optics & Technology. The one-meter new vacuum solar telescope (NVST) is currently the world's largest diameter vacuum solar telescope and is one of three more than one-meter diameter advanced global ground solar observation system.

It is jointly developed by Yunnan Observatory of Chinese Academy of Sciences, Nanjing Institute of Astronomical Optics & Technology and Nanjing Astronomical Instrument Company. In 2010, NVST came into observation at observation base of Fuxian Lake in Yunnan Observatory. It becomes the main equipment of China's solar physics and space sciences subject which will observe optical and near-infrared on sun.　

Pro. Gu told us that the biggest "challenge" of solar telescope need be faced was high temperature and this point was deferent from night astronomical telescope. Like this one-meter diameter telescope, the mirror which was located at main focus during observation seemed continued broiled electric furnace with 300 watts to 500 watts.

It was able to "see" 1/10 "skin" surface of the sun one time but it could absorb heat from the entire solar. If without treatment, such a high temperature might burn the reflective film. The uneven heat in the tube could lead to poor seeing and would greatly affect the fine observed effect.

Pro. Gu indicated that the "cooling paste" which NVST currently installed was "heat pipe" adding "cooling" system. The heat pipe of two 12mm thickness and at right angles distribution clung to the mirror and exported heat from vacuum tube. Then making use of circulating water cooled and reciprocated.

Under this situation, the temperature of the mirror in the "bull's-eye" position could be maintained 20 ℃ to 30 ℃ higher than the surrounding environment.

Pro. Gu hoped that it would be possible to improve the telescope "cool" efficiency so that the "heat paste” would be changed into a "normal temperature paste". According to his conception, he wanted to transform the "heat pipe" into "thin version of” 5mm micro-pipe. In the way of four symmetric cross, they would be attached to the telescope "face".

Two entering pipes and two exiting pipes would be for importing cold and outputting heat. If successful transformation, the main focus temperature would cool to the temperature of the surrounding mirror which was from ±1 ℃ to ± 2 ℃.

"Cooling system" upgrade of NVST will be completed this year.

Pro. Gu told us that Yunnan Observatory had planned to add more equipment such us magnetic field analyzer and spectrometer to NVST. In that way, it would be possible to extend research capabilities and explore more mysteries of the sun. (The end)

Fig1 Upgrading of the World's Largest Vacuum Solar Telescope by Installation of Power "Cooling Paste"