Basic Science

New Findings in Middle-Infrared Strong Field Physics

Xu Zhizhan, Member of CAS and Prof. Cheng Ya from the Key Laboratory of High Field Laser Physics, the Shanghai Institute of Optics and Fine Mechanics, CAS, Prof. Liu Xiaojun from the Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, CAS and Associate Prof. Chen Jing from the Beijing Institute of Applied Physics and Computational Mathematics, Chinese Academy of Engineering Physics achieved an important result in the cutting edge research of middle-infrared strong field physics. They carried out experiments of above-threshold ionization of atom at strong field and in-depth theoretical research by use of the tunable middle-infrared band ultra-intense and ultra-short laser platform newly built by the Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics. They found in the experiments that in a middle-infrared band (for example, 2,000nm wavelength) strong laser field, the electron energy spectrum of above-threshold ionization of atom presents a surprising peak-shaped (even double peaks) new structure at the low-energy end and further revealed that the long range Coulomb interaction plays an important role under long wavelength. The original finding was published in the latest issue of Physical Review Letters.

Superconducting High-Frequency Equipment for BEPCII

Recently, the Beijing electron-positron collider (BEPCII) 500MHz superconducting cavity high-order mode absorber independently developed by the Institute of High Energy Physics, CAS successfully passed low-power absorption characteristic test and high-power thermal load test. The absorption rate of high-order mode reached 60% and load absorption high-power of individual loaded high-order mode absorber was above 4.4kW, which reached the level of performance test of the same type of equipment in the world. It should be noted that the high-power test was accomplished on the high-power test board (a major equipment project of CAS) newly developed by the Institute of High Energy Physics. This marked that after the successful development of high-power input coupler for large-size superconducting accelerator, the Institute of High Energy Physics has made another breakthrough in its independent development of key superconducting high-frequency equipment. To develop and master key technology and develop key equipment that can substitute imported equipment, the high-frequency researchers of the Accelerator Center, the Institute of High Energy Physics began to tackle crucial issues jointly with the General Research Institute for Nonferrous Metals since 2008, in order to develop superconducting high-frequency cavity equipment independently. After repeated experiments, with the assistance from domestic enterprises, they finally developed the first experimental prototype of 500MHZ superconducting high-frequency cavity high-order mode absorber in China, in which absorption rate reached 60% and load absorption power reached above 4.4kW. This breakthrough laid an important foundation for the replacement of expensive imported equipment of the same type in the operation and backup of BEPCII superconducting high-frequency system.