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Published in last 1 year |  In last 2 years |  In last 3 years |  All Please wait a minute... For selected: Download citations EndNote Ris BibTeX Toggle thumbnails Select A 658-W VCSEL-pumped rod laser module with 52.6% optical efficiency Xue-Peng Li(李雪鹏), Jing Yang(杨晶), Meng-Shuo Zhang(张梦硕), Tian-Li Yang(杨天利), Xiao-Jun Wang(王小军), and Qin-Jun Peng(彭钦军) Chin. Phys. B, 2022, 31 (8): 084207.   DOI: 10.1088/1674-1056/ac728f Abstract （386）   HTML （0）    PDF （1488KB）（252）       Knowledge map    A high-efficiency and high-power vertical-cavity surface-emitting laser (VCSEL) side-pumped rod Nd:YAG laser with temperature adaptability are demonstrated. The VCSEL side-pumped laser module is designed and optimized. Five VCSEL arrays are symmetrically located around the laser rod and a large size diffused reflection chamber is designed to ensure a uniform pump distribution. Furthermore, the absorbed pump power distribution of the rod is simulated to verify the uniformity of the pump absorption. Finally, a proof-of-principle experiment is performed in short linear cavity laser with single laser module. A continuous-wave output power of 658 W at 1064 nm is obtained, the corresponding optical-to-optical efficiency is 52.6%, and the power variations are ±0.7% over 400 s and ±3.1% over the temperature range from 16 ℃ to 26 ℃. To the best of our knowledge, this is the highest output power and the highest optical-to-optical efficiency ever reported for VCSEL pumped solid-state lasers. By inserting a telescopic module into the cavity and optimizing the TEM00 mode volume, the average beam quality is measured to be M2=1.34 under an output power of 102 W. The experimental results reveal that such a high power rod laser module with temperature stability is appropriate or field applications. Select Design and high-power test of 800-kW UHF klystron for CEPC Ou-Zheng Xiao(肖欧正), Shigeki Fukuda, Zu-Sheng Zhou(周祖圣), Un-Nisa Zaib, Sheng-Chang Wang(王盛昌), Zhi-Jun Lu(陆志军), Guo-Xi Pei(裴国玺), Munawar Iqbal, and Dong Dong(董东) Chin. Phys. B, 2022, 31 (8): 088401.   DOI: 10.1088/1674-1056/ac6b26 Abstract （327）   HTML （0）    PDF （1232KB）（274）       Knowledge map    To reduce the energy demand and operation cost for circular electron positron collider (CEPC), the high efficiency klystrons are being developed at Institute of High Energy Physics, Chinese Academy of Sciences. A 800-kW continuous wave (CW) klystron operating at frequency of 650-MHz has been designed. The results of beam-wave interaction simulation with several different codes are presented. The efficiency is optimized to be 65% with a second harmonic cavity in three-dimensional (3D) particle-in-cell code CST. The effect of cavity frequency error and mismatch load on efficiency of klystron have been investigated. The design and cold test of reentrant cavities are described, which meet the requirements of RF section design. So far, the manufacturing and high-power test of the first klystron prototype have been completed. When the gun operated at DC voltage of 80 kV and current of 15.4 A, the klystron peak power reached 804 kW with output efficiency of about 65.3% at 40% duty cycle. The 1-dB bandwidth is ±0.8 MHZ. Due to the crack of ceramic window, the CW power achieved about 700 kW. The high-power test results are in good agreement with 3D simulation. Select High-precision nuclear magnetic resonance probe suitable for in situ studies of high-temperature metallic melts Ao Li(李傲), Wei Xu(许巍), Xiao Chen(陈霄), Bing-Nan Yao(姚冰楠), Jun-Tao Huo(霍军涛), Jun-Qiang Wang(王军强), and Run-Wei Li(李润伟) Chin. Phys. B, 2022, 31 (4): 040706.   DOI: 10.1088/1674-1056/ac4a70 Abstract （429）   HTML （5）    PDF （1503KB）（456）       Knowledge map    High-temperature nuclear magnetic resonance (NMR) has proven to be very useful for detecting the temperature-induced structural evolution and dynamics in melts. However, the sensitivity and precision of high-temperature NMR probes are limited. Here we report a sensitive and stable high-temperature NMR probe based on laser-heating, suitable for in situ studies of metallic melts, which can work stably at the temperature of up to 2000 K. In our design, a well-designed optical path and the use of a water-cooled copper radio-frequency (RF) coil significantly optimize the signal-to-noise ratio (S/NR) at high temperatures. Additionally, a precise temperature controlling system with an error of less than ±1 K has been designed. After temperature calibration, the temperature measurement error is controlled within ±2 K. As a performance testing, 27Al NMR spectra are measured in Zr-based metallic glass-forming liquid in situ. Results show that the S/NR reaches 45 within 90 s even when the sample's temperature is up to 1500 K and that the isothermal signal drift is better than 0.001 ppm per hour. This high-temperature NMR probe can be used to clarify some highly debated issues about metallic liquids, such as glass transition and liquid-liquid transition.