From the “E.O. Lawrence would be jealous department” and the University of Texas Austin comes this bit of interesting news (h/t to “View From the Solent”). Full disclosure, I made a cyclotron myself and went to the National Science Fair with it in 1975. It was about the size of desk, and I powered its magnet system with my dad’s DC welder. I got about 2 MeV out of it. – Anthony
Particle Accelerator That Can Fit on a Tabletop Opens New Chapter for Science Research
AUSTIN, Texas — 
Physicists at The University of Texas at Austin have built a tabletop particle accelerator that can generate energies and speeds previously reached only by major facilities that are hundreds of meters long and cost hundreds of millions of dollars to build.
“We have accelerated about half a billion electrons to 2 gigaelectronvolts over a distance of about 1 inch,” said Mike Downer, professor of physics in the College of Natural Sciences. “Until now that degree of energy and focus has required a conventional accelerator that stretches more than the length of two football fields. It’s a downsizing of a factor of approximately 10,000.”
The results, which were published this week in Nature Communications, mark a major milestone in the advance toward the day when multi-gigaelectronvolt (GeV) laser plasma accelerators are standard equipment in research laboratories around the world.
Downer said he expects 10 GeV accelerators of a few inches in length to be developed within the next few years, and he believes 20 GeV accelerators of similar size could be developed within a decade.
Downer said that the electrons from the current 2 GeV accelerator can be converted into “hard” X-rays as bright as those from large-scale facilities. He believes that with further refinement they could even drive an X-ray free electron laser, the brightest X-ray source currently available to science.
A tabletop X-ray laser would be transformative for chemists and biologists, who could use the bright X-rays to study the molecular basis of matter and life with atomic precision, and femtosecond time resolution, without traveling to a large national facility.
“The X-rays we’ll be able to produce are of femtosecond duration, which is the time scale on which molecules vibrate and the fastest chemical reactions take place,” said Downer. “They will have the energy and brightness to enable us to see, for example, the atomic structure of single protein molecules in a living sample.”
To generate the energetic electrons capable of producing these X-rays, Downer and his colleagues employed an acceleration method known as laser-plasma acceleration. It involves firing a brief but intensely powerful laser pulse into a puff of gas.
“To a layman it looks like low technology,” said Downer. “All you do is make a little puff of gas with the right density and profile. The laser pulse comes in. It ionizes that gas and makes the plasma, but it also imprints structure in it. It separates electrons from the ion background and creates these enormous internal space-charge fields. Then the charged particles emerge right out of the plasma, get trapped in those fields, which are racing along at nearly the speed of light with that laser pulse, and accelerate in them.”
The interior of the vacuum chamber in which the acceleration occurs. The laser beam arrives from the right. The gas cell, within which the acceleration of electrons occurs, is in the center of the chamber. The actual acceleration occurs over a distance of about an inch.
Downer compared it to what would happen if you threw a motorboat into a lake with its engines churning. The boat (the laser) makes a splash, then creates a wave as it moves through the lake at high speed. During that initial splash some droplets (charged particles) break off, get caught up in the wave and accelerate by surfing on it.
“At the other end of the lake they get thrown off into the environment at incredibly high speeds,” said Downer. “That’s our 2 GeV electron beam.”
Former UT Austin physicist Toshiki Tajima and the late UCLA physicist John Dawson conceived the idea of laser-plasma acceleration in the late 1970s. Scientists have been experimenting with this concept since the early 1990s, but they’ve been limited by the power of their lasers. As a result the field had been stuck at a maximum energy of about 1 GeV for years.
Downer and his colleagues were able to use the Texas Petawatt Laser, one of the most powerful lasers in the world, to push past this barrier. In particular the petawatt laser enabled them to use gases that are much less dense than those used in previous experiments.
“At a lower density, that laser pulse can travel faster through the gas,” said Downer. “But with the earlier generations of lasers, when the density got too low, there wasn’t enough of a splash to inject electrons into the accelerator, so you got nothing out. This is where the petawatt laser comes in. When it enters low density plasma, it can make a bigger splash.”
Downer said that now that he and his team have demonstrated the workability of the 2 GeV accelerator, it should be only a matter of time until 10 GeV accelerators are built. That threshold is significant because 10 GeV devices would be able to do the X-ray analyses that biologists and chemists want.
“I don’t think a major breakthrough is required to get there,” he said. “If we can just keep the funding in place for the next few years, all of this is going to happen. Companies are now selling petawatt lasers commercially, and as we get better at doing this, companies will come into being to make 10 GeV accelerator modules. Then the end users, the chemists and biologists, will come in, and that will lead to more innovations and discoveries.”
1/10,000 > 0
Well I’m impressed; but I am still inclined to cry foul.
Looking at the photo of the “desk top” 2GEV electron accelerator, I had a hard time identifying which bulge on it was the petaWatt laser that drives it.
Still I’m impressed. Too bad Anna v has been absent for a good bit. The fact that you can accelerate electrons to 2 GEV in just an inch of travel is astonishing. The Stanford two mile linac was built to overcome the EM radiation limit, that restricts the energy of accelerated charged particles, and electrons in particular. Of course Hertz / Maxwell showed that accelerated electric charge; aka varying currents travelling a non zero distance, must radiate EM waves (antenna theory; electric dipoles and the like).
Niels Bohr decided to unilaterally abrogate that rule, without any justification, so long as the electron remained in one of his sacred orbits. Arnold Sommerfeld compounded the felony, by allowing elliptical orbits as well. The fact that such electrons were continuously accelerating, and with variable acceleration, for Arnies ovals, didn’t seem to bother them.
Well I guess Quantum mechanics came along and saved their skins, by straightening out the mess.
So today, accelerated electric charges still radiate; particularly electrons. well that’s a pretty short get up and go in just 25 mm to 2 GEV.
I just figured out that my ordinary desk to power supply, that I can run my electric toothbrush from, can deliver 3.84 Mega Watts per square metre, and its about as tiny as their accelerator.
Well I don’t know how big the PG&E nuke or hydrodam on the other end is.
And yes; I too am impressed with Anthony’s 2 MEV cyclotron. Now that takes balls. I never ever aspired to anything that outlandish. My brother and I did try to make our own firecracker factory, when I was about eight. We had the rolling paper strips around a toothpick, to form the casings down pat; sat up in bed all night working our production line. We were still researching the “fire” part of the program, when someone let the cat out of the bag, and we went bankrupt. Well specifically, my brother dropped the pillowcase full of thousands of casings, and we made a hell of a racket trying to pick them all up. Adults just have no imagination.
Well heck; open my mouth and Anna v pops out of the woodwork. Welcome back Anna.
From george e. smith on June 21, 2013 at 10:25 pm:
Well she is a retired particle physicist in Greece, the bankrupt country of never-ending austerity measures. These days she has to rely on free internet access down at the public library, and the money she earns by teaching quark classifications to passerby in the village square is rarely enough to pay the bribes to the librarians so she can get on the schedule.
Yes I’m joking. Well, I hope I’m joking. Actually things have been sounding pretty desperate over there, I might be accidentally telling the truth. Heck, that could be even nicer than the reality.
Is it too late for her to evacuate before the entire economy collapses and she has to fight feral cats over pigeon eggs?
I spent a dozen years building and operating a 1 GeV Free Electron Laser. Our accelerator was 450 feet long so I am pretty impressed if you can can compress 450 feet into one inch. That represents a 5,000 to one improvement in acceleration gradient. Even if the PetaWatt Texas laser takes up 1,500 square feet that is a big improvement over the DFELL with its 450 foot long accelerator tunnel and 20,000 square foot sychrotron building costing roughly $30 million.
FELs based on 1 GeV electron beams are routine but this new technology may make it more affordable. Based on a 1 Gev electron beam the Duke university HIGS project uses inverse Compton scattering to produce the world’s brightest tunable polarized gamma ray source operating from a few MeV to a theoretical limit of 140 MeV.
The energy of photons produced by inverse Compton in a head on collision is given by this equation:
E(gamma photon) = E(incident photon) * 4 * (gamma)^2
Where “gamma” is proportional to the electron beam energy. If the electron beam has an energy of 1 GeV the “gamma” is ~2,000. The gamma for 20 GeV electrons is roughly 40,000. Assuming one starts with a visible light photon (~2 eV) the resultant gamma ray has an energy of up to 2 * 4 * 40,000 * 40,000 = 12.8 GeV.
If it proves possible to produce precisely tunable photons in this energy range it will be possible to stimulate nuclear reactions that normally occur only in the core of stars. ITER may turn out to be an expensive waste of time.
Inverse Compton scattering is believed to be the process that accounts for GRBs (Gamma Ray Bursters).
anna v, June 21, 2013 at 8:59 pm,
I never thought of myself as a “High Energy Physicist” given that the Duke FELL synchrotron operated at a measly 1.2 GeV on a good day, downhill and with the wind behind us. My idea of “High Energy” was the “Super Collider” that never happened, the Tevatron (thank y’all for those high precision 500 kW power supplies and spare parts) and the LHC.
Hmm, all very impressive, but if you really want a kitchen-table scale atom smasher dig out your dusty old copy of Scientific American for Jan 1959. On the Amateur Scientist pages you’ll find “How to Make an Electrostatic Machine to Accelerate Both Electrons and Protons”. It’s only good for about 0.5MeV, and you still need a reasonable vacuum pump, but it’ll certainly get you a reputation in the neighbourhood.
george e. smith says:
June 21, 2013 at 10:25 pm
Hi George
I am here everyday. I have wattsup as my home page :). I am not commenting often because climate science has started to bore me, since it goes in circles, and anyway I am waiting for the other shoe to drop as far as the demise of AGW. Also I have found a physics forum that I am active on since there are a lot of interesting questions there. http://physics.stackexchange.com/ .
I don’t know that much about particle physics…but..
can I have one, please !!
Darned if I know where I would put it ,though !
This has ‘Sheldon Cooper’ and ‘set fire to my hamster’ written all over it! 🙂
I’m good at making little puffs of gas!
Didn’t Sheldon build one of these in his garage when he was 12?
Cool site, Anna V. Thanks for the link
“CJohnson says:
June 21, 2013 at 4:57 pm
Well “table top” is a bit misleading, its being driven by a petawatt laser. Admittedly, 1500 square foot room is an improvement but thats the size of a house last I checked.”
Well, Mister Johnson, it’s “table top” size for a Texas house. I have a bowling alley in my walk-in closet in San Antonio! We provide Segways so guests can get from the living room to the dining room before dinner gets cold. By the time I get from the bedroom to the kitchen each morning, I’ve worn out a pair of cowboy boots. My garage is in another county, and my backyard IS another county. My shower is so big it has its own weather. And furthermore…;)
How about a Field Plasma Rifle in the 40 watt range!
george e. smith & anna v,
Here is the HIGS link:
http://www.tunl.duke.edu/web.tunl.2011a.higs.php
FELs are wonderful for “Inverse Compton Scattering” because the photons inside the laser cavity automatically align with the electron beam that creates them:
http://eud.gsfc.nasa.gov/Volker.Beckmann/school/download/Longair_Radiation3.pdf
An irony that an organization of a country supposed to be the champion of liberty does not allow to differ.Is it a bad history again repeated ?
Kadaka (KD Knoebel) says:
June 21, 2013 at 11:08 pm
Well she is a retired particle physicist in Greece, the bankrupt country of never-ending austerity measures.
True, we still have not bottomed. Thanks for your concern.
Well, I hope I’m joking. Actually things have been sounding pretty desperate over there,
Greece is being used as a guinea pig to the theory of internal deflation. . Don’t try this at home.
It works badly.
Salaries and pensions have been cut from 30 to 60 percent , the high cuts on high salaries and pensions, which sort of squeezes everybody. Taxes upon taxes are imposed reducing income even further. We have had years in Greece during and after the junta in 1967, where inflation was 30% and the drachma was being devalued from month to month. We survived with little social unrest. I do not know the outcome of this experiment, but I think that explosions are not far away, because people, the hoi polloi, do not understand that we are bankrupt. Had we gotten out of the eurozone in 2009 when the trouble started we would have been much better off socially even if in the same place financially. After all, with all the billions in lending from the EU etc our public debt is bigger than it was in 2009. The borrowed money goes into paying interests on the debt!. I think the arm of the government at the time was twisted not to get out of the eurozone, because the EU countries ( call me Germany) had a lot of the debt. In the intervening years they got rid of it while we flounder in bigger and bigger debt with worse legal ramifications. The Grexit is not an option now because of these stricter bonds. 🙁 .
Wow. This is fantastic. Could it be a path to mass (no pun intended) production of anti-matter. Then we have rocket fuel, baby!
cedarhill says June 21, 2013 at 4:47 pm
The Texax laser takes up about 1,500 sq. ft. in a clean room. At over 30 feet, it’d be hard to put that on most “desktops”. However, even with the room-size laser — wow!
Tie this in with work on high-power solid state lasers.
“”””…..anna v says:
June 22, 2013 at 12:38 am
george e. smith says:
June 21, 2013 at 10:25 pm
Hi George
I am here everyday. I have wattsup as my home page :). I am not commenting often because climate science has started to bore me, since it goes in circles, and anyway I am waiting for the other shoe to drop as far as the demise of AGW. Also I have found a physics forum that I am active on since there are a lot of interesting questions there. http://physics.stackexchange.com/ ……””””
Well I think you’re a whole lot smarter than I am Anna; so I should check out your Physics site.
I once sat at a card table drinking a beer with the Canadian Nobel Physicist who showed that Quarks exist (he’s a SLAC guy). Next time I have that opportunity, I want to ask him what’s with “Black Body Radiation” because nobody could have ever observed it; you would have to throw out everything about Maxwell’s equations and Fresnel reflection (polarized) to have a real black body; so why is it such an important non thing in 20th century Physics.
But I have to admit, that I tire of all the statistical analysis, where everybody is trying to find the correct detrending, and straight line fit to an obviously non straight line data set, to determine the magic R^2 and p or sigma, that will pop out of the curtain, and prove that MMAGWCC really exists, or really doesn’t exist.
I’m quite confident, that so long as the sun shines, and the oceans remain, that most of the world’s surface area will remain comfortably livable, at least until the next mile wide asteroid makes a direct hit on earth; that H2O stuff is one devilishly clever feedback stuff, that keeps us all safe and comfortable, no matter how much CO2 humans and Mother Gaia, spew out into the atmosphere.
When the big Indonesian tsunami, hit Bangladesh, all the cows and elephants ran for the high ground, while all the dumb and dumberer humans ran out onto the mudflats to pick up their free fish.
But we do all hope that Greece figures out how to make it through the current situation.
I learned today, that the current executive branch administration of the United States Government, has just 8% of its staff, who EVER had a job in a real business; down to and including a lemonade stand.
That is the lowest percentage, in our entire (US) history. And it is just one fourth of whichever previous administration is in second place.
We have THE most incompetent bunch of dunderheads running our country, that we have ever had. Average exec branches have had around 50 % people who EVER had a real job.
So pray for us too. Obamacare kicks in, in just 4 months.
“Downer compared it to what would happen if you threw a motorboat into a lake with its engines churning. The boat (the laser) makes a splash, then creates a wave as it moves through the lake at high speed. During that initial splash some droplets (charged particles) break off, get caught up in the wave and accelerate by surfing on it.”
If you are ionizing a gas and creating a plasma that is highly structured, then double layers of charge are being formed. When a particle passes through a double layer, it is accelerated. I am not sure there is any surfing going on here.
Reblogged this on The Science Blog.
Inch and GeV Mixed units?