If you get a chance to visit a computer history museum and see some of the very old computers, you’ll think they took up a full room. But if you ask, you’ll often find that the power supply was in another room and the cooling system was in yet another. So when you get a computer that fit on, say, a large desk and maybe have a few tape drives all together in a normal-sized office, people thought of it as “small.” We’re seeing a similar evolution in particle accelerators, which, a new startup company says, can be room-sized according to a post by [Charles Q. Choi] over at IEEE Spectrum.
Usually, when you think of a particle accelerator, you think of a giant housing like the 3.2-kilometer-long SLAC accelerator. That’s because these machines use magnets to accelerate the particles, and just like a car needs a certain distance to get to a particular speed, you have to have room for the particle to accelerate to the desired velocity.
A relatively new technique, though, doesn’t use magnets. Instead, very powerful (but very short) laser pulses create plasma from gas. The plasma oscillates in the wake of the laser, accelerating electrons to relativistic speeds. These so-called wakefield accelerators can, in theory, produce very high-energy electrons and don’t need much space to do it.
The startup company, TAU Systems, is about to roll out a commercial system that can generate 60 to 100 MeV at 100 Hz. They also intend to increase the output over time. For reference, SLAC generates 50,000 MeV. But, then again, it takes two miles of raceway to do it.
The initial market is likely to be radiation testing for space electronics. Higher energies will open the door to next-generation X-ray lithography for IC production, and more. There are likely applications for accelerated electrons that we don’t see today because it isn’t feasible to generate them without a massive facility.
On the other hand, don’t get your checkbook out yet. The units will cost about $10 million at the bottom end. Still a bargain compared to the alternatives.
You can do some of this now on a chip. Particle accelerators have come a long way.
Photo from Tau Systems.
Oh this is so exciting!! IMHO electron beams or the way to go for rad testing for space environments. You get a scale that resembles closer to a laser system while getting some of the penetration power of something like a proton or heavy ion beam. Best of both worlds.
Of course, the devil is in the details concerning spot size, penetration depth, charge deposition etc.
Research is actively being conducted so that we can draw equivalence LET’s produced by between e-beams (and laser) systems, and old fashion proton and heavy ion testing.
The Varian Truebeam radiation therapy system contains a LINAC in the 22Mev range. It’s definitely less than room size. Cost is about $4M.
My understanding is that the plasma oscillates in the wake of the electron beam. The laser converts the gas to plasma, the incoming electron beam repels free electrons in the plasma creating a positively charged tube, and then those repelled electrons are pulled back into the positively charged tube in time to repel the tail end of the beam, giving it a forward kick. It’s a way to transfer energy/momentum from the front of the beam to the back of the beam. There’s no free lunch happening.
Also, at SLAC the beam acceleration is accomplished with RF fields generated by klystrons. The magnets are used for steering and focusing, but they don’t add energy to the beam.
It’s cool to see this technique being commercialized. I was a summer intern with one of the first groups doing wakefield experiments in 2001.