Recently, the EUV free electron laser device jointly developed by the Dalian Institute of Chemical Physics, Chinese Academy of Sciences and the Shanghai Institute of Applied Physics, "Dalian Light Source," issued the strongest EUV laser pulse in the world with a single picosecond 1 picosecond equals one trillionth of a second) Laser pulses generate 140 trillion photons and the 100 meter total length of the device is the brightest and fully adjustable EUV free-standing laser source in the world.

Free electron laser is the latest generation of advanced light source in the world. It is also an important direction competing developed countries in the world today. It has important application prospect in scientific research and national defense science and technology development.

Dalian Light Source is the first large-scale free electron laser research user device in China. It is the only free electron laser device in the world that operates in the extreme ultraviolet band and the brightest extreme ultraviolet light source in the world. It is also another important exploration of our country in this field after "Hefei Light Source" and "Shanghai Light Source". What is the extreme ultraviolet light, what is the basic principle of this advanced large-scale scientific device and what are the applications?

Bright light, short pulse, the micro-world see more clearly

Humans already know that many physical and chemical processes are inherently atomic and molecular movements. To control or utilize these processes, it is necessary to study the reaction mechanism of the atoms and molecules involved therein, and to accurately and highly sensitively probe the atoms and molecules involved.

Since the 19th century, electricity and electromagnetic waves have become the most important media and means for mankind to recognize and perceive the physical world. For example, microphones convert sound into electrical signals for further processing and transmission. The most direct way for people to study the reaction mechanism of atoms and molecules is to change them into electrical signals that are easy to identify and process. The process is to "knock" (ionize) the electrons in atoms or molecules to get the structural and dynamic information of atomic molecules and substances, and then to explore the mysteries of the physical world at the micro level.

Modern physics has proved that light has wave-particle duality, which is both electromagnetic wave and particle. Photon itself with energy, the shorter the wavelength, the higher the photon energy. When the wavelength of light is as short as about 100 nanometers, the energy of a photon is sufficient to ionize an atom or molecule without breaking it. The light in this band is called extreme ultraviolet light. However, due to the scientific experiments, the need to detect the number of atoms or molecules may be very small, there is a very short time, the general EUV light source can not meet this need, it must have a high brightness EUV light source, that is, extreme ultraviolet laser . "The light source is bright and the microscopic world can be seen more clearly. With a short pulse, we can see the ultra-fast processes of molecules and atoms in the physical and chemical changes," said Academician Yang Xueming, deputy director of the Dalian Institute of Chemical Physics.

The brightest "flash", the fastest "shutter", allows molecules, atoms "nowhere to hide"

EUV laser can ionize almost all the atoms and molecules that make up common substances. Therefore, EUV laser can not generate and amplify in ordinary matter, and it can only be produced in "special matter" which is separated from the nucleus and separated Existence of free state electrons.

According to the principle of electrodynamics, accelerated electrons will radiate electromagnetic waves outwards, and the oscillating electrons will radiate electromagnetic waves very strongly. Commonly used wireless signals, whether it is a television or a cell phone, transmit electromagnetic waves by driving the electrons to oscillate back and forth in the antenna.

"Dalian light source" by the accelerator, undulator and beam station composed of three parts. The pulse width of a few picosecond pulse laser (drive laser) in the photocathode hit a cluster of high-density pulsed electrons, and then use a linear accelerator to accelerate the pulsed electron beam to 300 million electron volts of energy, electron velocity Very close to the speed of light. Another picosecond or near-time intense laser (seed laser) impinges on this high-energy electron beam. The electrons in the electron beam are spatially redistributed (modulated) at the laser wavelength by the action of the seed laser, The modulated electron beam is then allowed to continue through a series of periodically varying magnetic fields. In the periodic magnetic field, electrons will fly forward at the speed of light while swinging from side to side and radiate light forwardly. Light emitted throughout the way will be superimposed on the increase, while the electron itself is also modulated by the light of their own spatial distribution of space, allowing electrons to more intense radiation, the appropriate choice of periodic magnetic field strength, will make the seed laser A harmonic component is sharply self-excited and saturated as described above, thereby outputting an extreme ultraviolet laser.

"Dalian Light Source has the brightest 'flash', the peak power of 100 billion times the brightness of sunlight 100 billion times the fastest 'shutter', the light length can reach femtosecond (1 femtosecond is equal to one thousand One hundred millionth of a second), picoseconds, not only allows molecules, atoms 'nowhere to hide', but also to them 'film', the whole process of physical and chemical reactions dynamically recorded. "Shanghai Institute of Applied Physics Zhao Zhentang long with a series of metaphors to illustrate the "Dalian Light" great use.

Metal Seated Butterfly Valve

Double-eccentric metal-to-metal sealed Butterfly Valve

Summary:

Flange double-eccentric metal-to-metal sealed butterfly valve is operated by worm gear to decelerate to drive the disc to rotate within 90°.It can be applied to cut off or regulate the flow of media. The valve can be actuated by operating lever, handle wheel, electric actuator or pneumatic actuator. Underground valve can be operated by an extended Spindle. No matter operated by electric actuator or pneumatic one, positions where the valve is opened and closed are all equipped with limit switches and indicating devices that synchronically show the opening state of the disc.

Structure:

Being double eccentric, when opened, the sealed ring of the disc is automatically off-seated after only a little degree of opening movement. The sealed ring completely bears no external pressure, which helps the valve keep longer life.

Butterfly valve has the capability of bi-directional sealing, which achieves no leakage in both primary and secondary directions, especially applicable to underground water-supplying network of pipes with circular multi-sources. If only unidirectional media, when installing the valve, the primary direction is of priority.

The position of sealed ring can be adjusted in all directions to modulate the compression of the sealing, which makes the valve able to be operated by minimum torque.

The base ring of the body and the sealed ring of the disc all employ stainless steel of excellent quality, which are competent of high temperature and anti-corrosion and long service life. The sealed structure of the valve uses divided-body design, dependable interchangeability, easy to apply and maintain.

As to those valves whose DN is equal or larger than 1200 mm, the disc applies the flying-disc design with a result of light weight, high rigidity, powerful strength, small flow–resistance and Low loss of pressure.

The stem and disc use a positioning pattern of non-penetration and pin–offset to avoid shearing and abrasion of the spline caused by frequent shifting of the upper stem and to prevent abnormal opening and closing of the valve.

Between the stem and the body [o" ring , a kind of environmentally-protecting rubber is applied, which not only achieves no maintenance but also reliable sealing, meanwhile, overcomes potential leakage when stuffing and sealing as well as prevents stuffing`s pollution of the water.

Technical characteristics:

Automatic assembly and coating product line and developed process-flow ensure the outstanding ability of anti-corrosion and flawless appearances of products.

Anti-corrosion performance:

Inside and outside surfaces of the body are coated with electrostatic epoxy resin powder. The coating is even and firm with good adhesion and excellent anti-corrosion.

Sanitary standard:

Non-toxic epoxy resin powder used comply with EN sanitary standard.

The coated resin is in accordance with standards of potable water

Applying area:

The valve can be used in potable water system, water supply and drainage, heat supply, gas, metallurgical industry, energy system and pipeline and so on.



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