A compact laser plasma accelerator that is a novel accelerator based on the interaction of ultra-intense laser and plasmas is being built now at Peking University. According to the results of experiments and numerical...A compact laser plasma accelerator that is a novel accelerator based on the interaction of ultra-intense laser and plasmas is being built now at Peking University. According to the results of experiments and numerical simulations, a beam line combining the advantages of quadrupole and analyzing magnets is designed to deliver proton beams with energy ranging from 1 to 44MeV, energy spread within ±5% and 10^6-8 protons per pulse. It turns out that the existence of space charge force of protons can be ignored for the increase of transverse and longitudinal envelopes even in the case of 10^9 protons in one pulse. To cope with the challenge to obtain a uniform distribution of protons at the final experiment target in laser acceleration, we manipulate the envelope beam waist in the Y direction to a proper position and obtain a relatively good distribution uniformity of protons with an energy spread of 0-±5%0.展开更多
A compact optical flip-flop with a directional coupler has been designed and analyzed. Using a narrow gap directional coupler, we have predicted the device length could be reduced down to 500μm from 1300μm.
As the first invention to efficiently harvest electricity from ambient mechanical energy by using contact electrification, the triboelectric nanogenerator has elicited worldwide attention because of its cost-effective...As the first invention to efficiently harvest electricity from ambient mechanical energy by using contact electrification, the triboelectric nanogenerator has elicited worldwide attention because of its cost-effectiveness and sustainability. This study exploits a superhydrophobic nanostructured aluminum tube to estimate electrical output for solid-water contact electrification inside a tubular system. The linearly proportional relationship of short-circuit current and open-circuit voltage to the detaching speed of water was determined by using a theoretical energy harvesting model and experimentation. A pioneering stick-type solid-water interacting triboelectric nanogenerator, called a SWING stick, was developed to harvest mechanical energy through solid-water contact electrification generated when the device is shaken by hand. The electrical output generated by various kinds of water from the environment was also measured to demonstrate the concept of the SWING stick as a compact triboelectric nanogenerator. Several SWING sticks were connected to show the feasibility of the device as a portable and compact source of direct power. The developed energy harvesting model and the SWING stick can provide a guideline for the design parameters to attain a desired electrical output; therefore, this study can significantly increase the applicability of a water-driven triboelectric nanogenerator.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 11575011the National Grand Instrument Project under Grant No 2012YQ030142
文摘A compact laser plasma accelerator that is a novel accelerator based on the interaction of ultra-intense laser and plasmas is being built now at Peking University. According to the results of experiments and numerical simulations, a beam line combining the advantages of quadrupole and analyzing magnets is designed to deliver proton beams with energy ranging from 1 to 44MeV, energy spread within ±5% and 10^6-8 protons per pulse. It turns out that the existence of space charge force of protons can be ignored for the increase of transverse and longitudinal envelopes even in the case of 10^9 protons in one pulse. To cope with the challenge to obtain a uniform distribution of protons at the final experiment target in laser acceleration, we manipulate the envelope beam waist in the Y direction to a proper position and obtain a relatively good distribution uniformity of protons with an energy spread of 0-±5%0.
文摘A compact optical flip-flop with a directional coupler has been designed and analyzed. Using a narrow gap directional coupler, we have predicted the device length could be reduced down to 500μm from 1300μm.
文摘As the first invention to efficiently harvest electricity from ambient mechanical energy by using contact electrification, the triboelectric nanogenerator has elicited worldwide attention because of its cost-effectiveness and sustainability. This study exploits a superhydrophobic nanostructured aluminum tube to estimate electrical output for solid-water contact electrification inside a tubular system. The linearly proportional relationship of short-circuit current and open-circuit voltage to the detaching speed of water was determined by using a theoretical energy harvesting model and experimentation. A pioneering stick-type solid-water interacting triboelectric nanogenerator, called a SWING stick, was developed to harvest mechanical energy through solid-water contact electrification generated when the device is shaken by hand. The electrical output generated by various kinds of water from the environment was also measured to demonstrate the concept of the SWING stick as a compact triboelectric nanogenerator. Several SWING sticks were connected to show the feasibility of the device as a portable and compact source of direct power. The developed energy harvesting model and the SWING stick can provide a guideline for the design parameters to attain a desired electrical output; therefore, this study can significantly increase the applicability of a water-driven triboelectric nanogenerator.
