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Home https://server7.kproxy.com/servlet/redirect.srv/sruj/smyrwpoii/p2/ Science https://server7.kproxy.com/servlet/redirect.srv/sruj/smyrwpoii/p2/ Physicists set a world record in desktop plasma acceleration with laser drilling

Physicists set a world record in desktop plasma acceleration with laser drilling



  Wakefield's acceleration can use different drivers. In the case of laser drive (above), a strong laser pulse is triggered in preformed plasma. In the proton-controlled scenario (bottom), a high-energy proton beam is sent into gas.
Enlarge / Wakefield's acceleration can use different drivers. In the case of laser drive (above), a strong laser pulse is triggered in preformed plasma. In the proton-controlled scenario (bottom), a high-energy proton beam is sent into gas. Particle accelerators can accelerate subatomic particles almost to the speed of light. The compromise is that this requires tunnels long miles, so such machines are usually huge and very expensive to build. Physicists want to build a viable version of the table that can accelerate particles by more than a few centimeters. Researchers from Laurence Berkeley's National Laboratory have already achieved the highest energy that was still recorded using so-called "plasma accelerators of wakefulness," and describe their work in a new article in Physical Review Letters . accelerators use modulated electric fields inside the metal cavities to accelerate electrons. The Big Hadron Accelerator at CERN in Switzerland is the largest one ever built with a 1
6-mile ring of superconducting magnets that serves to increase electrons to near-light speeds. In contrast, the acceleration of the plasma field of vision includes the launch of very intense, short bursts of laser light in a cloud of ionized gas (plasma). just like a speedboat, water will erupt after moving away from the lake. Then a second laser pulses more electrons into the plasma. If this is done right at the right time, these electrons can "surf" along the wake-up zone. The electrons pull the energy of the awake fields to gain more speed, just as a surfer can pick up the velocity that descends on the face of the wave.

Many different groups work to accelerate the plasma wakefield using different techniques. Earlier this month, CERN (AWAKE), which uses a high-energy proton kit as a wake-up driver rather than a laser impulse like the LBNL experiment, accelerates the electrons to 2 GeV earlier this month. AWAKE is a bit less than Berkeley's team in this respect, but the fact that two different methods of accelerating a smooth elevation on a planet make such a good improvement are good for the field.

  20 cm sapphire tubes, or capillaries, have been used to achieve the world record. Pipes are used to generate and limit plasma and accelerate electrons. "Src =" https://cdn.arstechnica.net/wp-content/uploads/2019/02/plasma1-640x427.jpg "width =" 640 "height =" 427 "srcset =" https: //cdn.arstechnica / 20p / content / uploads / 2019/02 / plasma1.jpg 2x
Click to enlarge / 20 cm sapphire tubes or capillary is used to achieve the world record. Pipes used to generate and limit plasma and accelerate electrons

Desktop accelerators have many promises for practical applications in medical therapies, X-ray imaging and possibly even security scanning technology. They are so promising that in 2015, the Gordon Foundation and Betty Moore awarded a $ 13.5 million grant to Stanford University to develop a shoe box shoe size accelerator by 2020. rooms and now fit into laptops, tablets and smartphones, the idea is ultimately to use micro-manufacturing techniques to build a manual particle accelerator (although the associated radiation will make it impossible to hold the device in hand).

The last article is based on the previous work of Team Leader Wim Limman in LBNL; now he is the director of the accelerator at DESY in Germany. In 2014, he and his team achieved a record acceleration of 4.25 gigawatts (GeV). They used an electric discharge to create plasma from gas contained in a short, thin tube. They then injected a pulse of laser light to form a channel in the ionized gas to contain the impulse – similar to how optical cables channel the light. They also create waves that capture free electrons and accelerate them to high energies.

Such a feat requires very precision and control over the laser beam, as it means pulsing through a 500-micron hole at 45 feet. Fortunately, LBNL has one of the most powerful and accurate lasers in the world of BELLA (Berkeley Lab Laser Accelerator). But as the 2014 experiment was successful, the laser light was so powerful that it continued to destroy the structure of the sapphire tube and, consequently, to lose its tight focus.

Leemans et al . knew that they would have to create plasma channels that were less dense in the middle to reach even higher energies. So they listened to a bit better by hiring a technique from the 1990s: shooting with the eight-nanosecond laser pulse in the tube immediately after unloading (after 420 nanoseconds to be accurate). The impulse will simultaneously heat the plasma and form a deeper channel capable of completely limiting the laser. This made it possible to use a longer 20cm tube compared to the 9cm tube used in the experiment in 2014.

  Picture of the electronic density profile of the plasma channel (blue) formed inside the capillary (gray ) with a combination of electric discharge and 9ns laser pulse (red / yellow). "src =" https://cdn.arstechnica.net/wp-content/uploads/2019/02/plasma2-640x419.jpg "width =" 640 "height =" 419 2x
Click to enlarge / Picture of the electronic density profile of the plasma channels (blue). [url=http://wwwcdnarstechnicanet/wp-content/uploads/2019/02/plasma2jpgformedvampirecollection(gray)scramblettelectricaldivision9nslazereimpulse(red/yellow)

G Bagdasarov / Keldysh Institute of Applied Math; A. Gonsalves, J.L. Vay / LBNL

"The development of stable plasma acceleration with energies close to 10 GeV is the cornerstone on the road from the laboratory to the first applications," said Limanse. "We have developed a new concept in the instrument box and, along with other acceleration, beam and ray control concepts existing in DESY, this will allow for compact electron sources."

But we're not there yet. Writing at Physics Florian Grüner of the University of Hamburg notes that the major achievement of 100 MeV energy in 2004 has essentially begun this new field of acceleration in the plasma field. He compared a cornerstone with the way the publication of the Jules Verne 1865 from Earth to Moon and the subsequent first man in space in 1961 launched the era of space exploration. But he thinks we have not yet reached the 1969 moon landing equivalent

. "It is not yet clear when the moon landing will take place in the form of a consumer facility to accelerate the wake field," writes Gruner. "The key to achieving this goal will be to develop an unprecedented level of control over all relevant parameters, meaning introducing entirely new" knobs "for things like the ultimate energy and energy distribution of accelerated particles.

DOI: Letters for Physical Review 2019. 10.1103 / PhysRevLett.122.054802 (for DOIs).


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