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China issues 5-year action plan for seawater desalination
Source: Xinhua| 2021-06-04 14:17:33|Editor: huaxia

BEIJING, June 4 (Xinhua) -- China has issued an action plan for seawater desalination utilization development over the next five years, according to China Science Daily on Friday.

The action plan, jointly issued by the National Development and Reform Commission (NDRC) and the Ministry of Natural Resources, is expected to promote the large-scale utilization of seawater desalination and ensure the safety of water resources in coastal areas.

China's seawater desalination scale will exceed 2.9 million tonnes per day by 2025, an increase of more than 1.25 million tonnes per day, according to the action plan.

Seawater desalination in coastal cities will increase by more than 1.05 million tonnes per day by 2025, while the island areas will see an increase of more than 200,000 tonnes per day.

The action plan also called for improving water supply security for seawater desalination, expanding the scale of seawater desalination in industrial zones, enhancing the water supply capacity for islands and ships, and exploring the application of desalination technology.

China has constructed 123 seawater desalination projects with a desalination capacity exceeding 1.6 million cubic meters per day, according to the NDRC.

The action plan called for strengthening technology development for seawater desalination, ensuring the safety of industrial and supply chains, and enhancing service capacity.
 

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OPTICS AND PHOTONICS * 11 JUNE 2021
Not just sorcery: scientists build an invisible portal : Research Highlights | Nature.com
‘Superscattering’ material is used to construct a mini-doorway that is invisible in the microwave portion of the spectrum.

Invisible doorways have long been the stuff of fiction: Harry Potter, for example, entered a hidden portal to catch a train at King’s Cross station in London. Now, a team has disguised a gateway in the real world.

The trick is to use a metamaterial — an artificial structure whose components collectively exhibit properties that the individual components do not. Metamaterials can be used to bend light in unusual ways and, with the right design, they can become ‘superscatterers’ that look larger than they really are.

Huanyang Chen of Xiamen University in China, Rui-Xin Wu at Nanjing University, also in China, and their colleagues built a superscattering metamaterial from iron-rich ceramic rods arranged in parallel. They placed their metamaterial on one side of a 5-centimetre-wide gateway. When they shone microwave radiation at the opening, the metamaterial stopped the waves from moving through the gateway, rendering it ‘invisible’ at microwave wavelengths.

The team confirmed that changing patterns of electron density at the surface of the metamaterial are responsible for repelling the light.

 

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Global Times @globaltimesnews
China state-affiliated media

#China on Wed launched its first virtual #EarthLab to simulate climate and ecological systems, which can predict climate variability, prevent natural disasters and improve China’s right to speak in intl negotiations.


3:16 PM · Jun 23, 2021

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China's first X-ray free electron laser device has acquired femtosecond "water window" band X-ray photos for the first time, marking that X-ray FEL research in China advanced from facility R&D phase to user operation phase which can compete globally.


5:58 PM · Jun 27, 2021
 

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Local researchers making 'molecular movies' with ultrafast lasers
Li Qian
19:06 UTC+8, 2021-06-28

Local researchers making 'molecular movies' with ultrafast lasers
Hu Weicheng / Ti Gong
The Shanghai Soft X-ray Free Electron Laser Facility


There's nothing surprising about using lasers to take pictures of molecules. But how about taking films? It's not just talk.

Last Thursday, in the city's innovation highland of Zhangjiang, researchers fired an ultra-intense ray of light at testing samples to take X-ray photos. It took just 100 femtoseconds.

One femtosecond is equal to one quadrillionth of a second. Think of it this way: nothing is faster than light in a vacuum, but even so, in one femtosecond, it can travel only 300 nanometers – about the diameter of a virus.

Sounds like something in a science-fiction movie? The Shanghai-XFEL Beamline Project (SBP) has made it possible.

"Our cameras can usually take a photo in one thousandth of a second. How about SBP? Its 'shutter speed' is one billion times faster. That is to say, it can capture the moments of some of the speediest processes, such as chemical reactions," said Liu Zhi, SBP general manager.

It enables researchers to get their first foot in the door for "molecular movies." Comparing cells as cities and proteins as cars, Liu said: "We want to see how proteins shuttle to and from."

Local researchers making 'molecular movies' with ultrafast lasers
Li Qian / SHINE
The Experimental Hall


The SBP makes up about one half of the 532-meter-long Shanghai Soft X-ray Free Electron Laser Facility (SXEFL), completing the final piece of the jigsaw puzzle. Following the accelerator, undulator and beamline commissioning, it has started data collection and is approaching full operation.

"Next, we will further optimize the facility performance to reach the perfect state, which is expected to open to users all over the world next year," Liu said.

Local researchers making 'molecular movies' with ultrafast lasers
Li Qian / SHINE
Inside the Experimental Hall


As the fourth-generation light source, it eclipses any other by state-of-the-art, free-electron laser technology.

It can generate laser pulses where all photons are identical, and detect tiny changes in material structures. The peak brightness of this X-ray laser is more than one billion times higher than the nearby Shanghai Synchrotron Radiation Facility (SSRF), a third-generation light source commonly known as the "Shanghai light source."

The facility is one of two in the world where such experiments have been performed in the "water window," the other being in the United States.

According to Liu Bo, vice general manager of SXEFL, more than 90 percent of the equipment in the facility is domestically developed and manufactured.

The so-called "water window" is occupied by soft X-ray radiation, with a wavelength range from 2.2 to 4.4 nanometers. This spectral window owes its name and significance to the fact that at those frequencies, photons are not absorbed by oxygen (and hence by water), but they are by carbon.

"In this range, water is more transparent to X-rays. But other essential life elements, such as carbon, still interact strongly with X-rays. Therefore, the 'water window' soft X-rays provide a unique opportunity for probing biological materials," Liu Zhi said. "Such ultrabright, ultrafast and coherent pulses enable scientists to take X-ray snapshots of atoms and molecules at work, revealing fundamental processes in materials, technology and living organisms."

Local researchers making 'molecular movies' with ultrafast lasers
Li Qian / SHINE
Inside the Experimental Hall


The SBP was jointly constructed by ShanghaiTech University and the Chinese Academy of Sciences' Shanghai Institute of Applied Physics and Shanghai Advanced Research Institute.

The SXFEL, together with SSRF, the Shanghai Super Intense Ultrafast Laser Facility and under-construction Shanghai Hard X-ray FEL Facility (SHINE), will form a cluster of photon science facilities, supporting a world-class photon science research center in Zhangjiang.

"They form a perfect combination. SSRF can discern structures of static systems. SXFEL can track the movements of molecules, but it is still limited and can only see things clearly in the nanometer scale. While SHINE can probe atomic structures," Liu Zhi said. "SHINE is expected to be completed by 2025. Once completed, it means that in Zhangjiang we will have all the cutting-edge light source facilities."
 

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High Energy Photon Source Starts Construction in Beijing
Jun 29, 2019

China' s High Energy Photon Source (HEPS), the country' s first high-energy synchrotron radiation light source and soon one of the world' s brightest fourth-generation synchrotron radiation facilities, began construction in Beijing' s Huairou District on June 29, 2019.

As one of the China' s key scientific and technological infrastructure projects under the 13th Five-year Plan, HEPS will be an important platform for original and innovative research in basic science and engineering.

HEPS is being built in Huairou' s Science City, located in northern Beijing, and will comprise accelerators, beamlines and auxiliary facilities. Prof. WANG Yifang, director of the Institute of High Energy Physics, said the overall shape of HEPS looked like a gigantic magnifier. “It means HEPS is a powerful tool for characterizing micro-structures.”

The storage ring of HEPS will be 1360.4m in circumference, with the electron energy of 6 GeV and the brightness of higher than 1×1022 phs/s/mm2/mrad2/0.1%BW.

"By using the 7BA (7-Bending achromat) lattice structure, the horizontal emittance of the electron beam could be smaller than 60 pm·rad, which is the main feature of fourth-generation diffraction limited light sources," said Prof. QIN Qing, HEPS project manager.

HEPS can accommodate more than 90 high-performance beamlines and stations. In the first phase, 14 public beamlines and stations will be available for researchers in the fields of engineering materials, energy and environment, medicine and food industry, petrochemistry and chemical industry, etc.

HEPS will provide high-brightness and high-coherence photon beam with a high energy up to 300 keV, while offering a nm level spatial resolution, ps level time resolution, and meV level energy resolution research platform.

In addition to providing conventional technical support for general users, HEPS will also offer an advanced technology support for research related to national development and key industrial needs.

HEPS will serve as a multi-dimensional, real-time, in-situ characterization platform for analyzing engineering materials and their structures. It can be used to observe the whole process of their evolution and provide information for the design and regulation of functional materials. HEPS will also become an important platform for international cooperation and basic science research.

Proposed in early 2016, HEPS was officially approved by the National Development and Reform Commission (NDRC), China's top economic planner, on Dec. 15, 2017. The estimated construction period is six and a half years.


High Energy Photon Source Starts Construction in Beijing---Chinese Academy of Sciences
China News 中国新闻网 @Echinanews
China state-affiliated media

China's Platform of Advanced Photon Source (PAPS) technology R&D project started trial operation on Monday in Beijing. The PAPS aims to provide strong support for construction, testing and technology R&D for the High Energy Proton Source (HEPS).
 

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A laser in Shanghai, China, has set power records yet fits on tabletops.
KAN ZHAN
Physicists are planning to build lasers so powerful they could rip apart empty space
By Edwin Cartlidge
Jan. 24, 2018 , 9:00 AM

Inside a cramped laboratory in Shanghai, China, physicist Ruxin Li and colleagues are breaking records with the most powerful pulses of light the world has ever seen. At the heart of their laser, called the Shanghai Superintense Ultrafast Laser Facility (SULF), is a single cylinder of titanium-doped sapphire about the width of a Frisbee. After kindling light in the crystal and shunting it through a system of lenses and mirrors, the SULF distills it into pulses of mind-boggling power. In 2016, it achieved an unprecedented 5.3 million billion watts, or petawatts (PW). The lights in Shanghai do not dim each time the laser fires, however. Although the pulses are extraordinarily powerful, they are also infinitesimally brief, lasting less than a trillionth of a second. The researchers are now upgrading their laser and hope to beat their own record by the end of this year with a 10-PW shot, which would pack more than 1000 times the power of all the world's electrical grids combined.

The group's ambitions don't end there. This year, Li and colleagues intend to start building a 100-PW laser known as the Station of Extreme Light (SEL). By 2023, it could be flinging pulses into a chamber 20 meters underground, subjecting targets to extremes of temperature and pressure not normally found on Earth, a boon to astrophysicists and materials scientists alike. The laser could also power demonstrations of a new way to accelerate particles for use in medicine and high-energy physics. But most alluring, Li says, would be showing that light could tear electrons and their antimatter counterparts, positrons, from empty space—a phenomenon known as "breaking the vacuum." It would be a striking illustration that matter and energy are interchangeable, as Albert Einstein's famous E=mc2 equation states. Although nuclear weapons attest to the conversion of matter into immense amounts of heat and light, doing the reverse is not so easy. But Li says the SEL is up to the task. "That would be very exciting," he says. "It would mean you could generate something from nothing."

The Chinese group is "definitely leading the way" to 100 PW, says Philip Bucksbaum, an atomic physicist at Stanford University in Palo Alto, California. But there is plenty of competition. In the next few years, 10-PW devices should switch on in Romania and the Czech Republic as part of Europe's Extreme Light Infrastructure, although the project recently put off its goal of building a 100-PW-scale device. Physicists in Russia have drawn up a design for a 180-PW laser known as the Exawatt Center for Extreme Light Studies (XCELS), while Japanese researchers have put forward proposals for a 30-PW device.


Continue -> Physicists are planning to build lasers so powerful they could rip apart empty space | Science | AAAS
Chinese breakthrough allows physicists to build the world’s most powerful laser
  • Technological leap would allow the firing of a laser 10,000 times more powerful than all the electricity grids in the world combined
  • With this development, the Station of Extreme Light could aid research in new materials, drugs and nuclear fusion energy
Stephen Chen in Beijing
Published: 7:00am, 2 Jul, 2021

 

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Scientists design novel “multistep pulse compressor” for 10s-100s PW lasers: From CPA to MPC
Update time: 2021-06-07

In a recent study, scientists at Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, designed a new “multistep pulse compressor(MPC)” for 10s-100s PW lasers. This work had been published in Optics Express on 19 May, 2021.

Petawatt (PW) laser pulses have opened up many important research fields in ultrahigh intensity physics, such as particle acceleration and nonlinear QED. One of the most significant bottlenecks in achieving 10s-100s PW lasers is the limited size and damage threshold of compression gratings. In the 100s PW laser designs of ELI and XCELS, about ten pulse compressors together with tiled-aperture beam-combining were used, which made the system complex, high cost, and difficult to achieve.

In 2020, a new in-house beam-splitting compressor based on the property that the damage threshold of gratings depends on the pulse duration was proposed to simultaneously improve the stability, save on expensive gratings, and simplify compressor size [Optics Express 28(15):22978(2020)].

Here, Prof. Jun Liu and his cooperators propose a novel MPC design considering both the temporal and the spatial properties. The idea is the same as chirped pulse amplification (CPA) method which obtained the 2018 Nobel Prize in Physics, as shown in Fig.1. The CPA method was proposed to solve the damage problem of laser crystal during improving the laser peak power in 1985 [Opt. Commun., 55(6):447(1985)].

In the CPA method, the damage problem of laser crystal is transferred to the laser pulse in the temporal domain to achieve the highest input/output laser energy, and then a pulse stretcher and a pulse compressor are designedly added before and after the laser amplifier, respectively, to solve the induced laser pulse duration issues. The proposed MPC method here is to solve the damage problem of compression gratings during enhancing the laser peak power to extremely high 100s PW level. The damage problems of gratings are transferred to the spatiotemporal properties to achieve the highest input/output pulse energy in the main four-grating compressor (FGC).

Then, a designed pre-compressor and a designed post-compressor are added before and after the FGC, respectively, to solve the induced spatiotemporal problems, as shown in Fig. 2. With this novel design, as high as 100 PW laser with single beam or more than 150 PW through combining two beams can be obtained by using currently available optics, which is simple, low cost, and together with improved laser stability in comparison to previous designs of 100s PW lasers.

This MPC design not only can be used in the SEL-100PW laser system, but also in all other PW laser facilities to improve the peak power and reduce the operation damage risk of gratings. Several 100s PW laser beam is expected to be obtained by using this MPC method in the future, which will further extend the ultra-intense laser physics research fields.

This research was supported by the National Natural Science Foundation of China, the Instrument Developing Project and the Strategic Priority Research Program of the Chinese Academy of Sciences, and Shanghai Municipal Science and Technology Major Project.

1625388626209.png
Fig.1 The comparison of CPA and MPC methods. (Image by SIOM)
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Fig.2 The principle of MPC. (Image by SIOM)
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