Wakefield Accelerators: The Future of Particle Colliders?

if I say particle accelerator this is what you picture right dozens of kilometers worth of tunnels electromagnetic plates and coils vacuum lines and delicate Hardware for most of the history of particle physics the motto has always been well I guess we need a bigger particle accelerator and up until recently that's been a very successful albeit expensive solution right now the LHC is the world's most powerful accelerator and at 27 kilometers in diameter it's easily the largest machine on earth designed by a team of 10,000 scientists and at a cost of seven and a half billion dollars it's a very expensive toy but it paid off one of the main goals of the project which was to discover the Higgs boson and prove the existence of the Higgs field happened very shortly after the accelerator came online and was followed by a nobel prize for the discovery in 2013 with all that money in size the maximum the LHC will ever be able to accelerate particles to is about eight to ten tera electron volts this is frankly an astonishingly large amount of power and yet to truly explore the depths of the universe it's several orders of magnitude do small apparently even at those high energies were barely seeing new particles pop out which has scientists confused so now the motto is beginning to change rather than build bigger accelerators scientists are trying to build better smaller ones or use old ones in new ways one of my favorite up-and-coming designs is something called a Wakefield accelerator these seem weird when you first start learning about them but are actually very clever before we can dive into that let's take a quick look at how with standard particle accelerator works fundamentally most particle accelerators work by sequentially pulling particles toward electrodes in a sequence imagine a long line of metal rings in a vacuum with a single electron placed at one end when you put some positive voltage on the first ring the electron is attracted to it before the electron makes it to the ring turn the voltage off already the electron is now moving pretty quickly forward as it passes the first ring put voltage on the second ring as before turn off the voltage before the electron reaches it of course you'll need to turn on each ring faster and faster but so long as you keep doing that the electron will continue to be pulled faster and faster as it's pulled towards the next rings most of the time this is done using things like radio frequency oscillation radio waves oscillate between positive and negative voltage up to several billion times per second so applying something like that to the rings allows you to turn them on very quickly particles that are put in the path will get accelerated pretty quickly up to a decent fraction of the speed of light and with energies measured in millions of volts or more the main issue is that all of this takes a lot of distance to get things up to really high speeds and energies so physicists build accelerators and rings so that the particles can go through a bunch of times and slowly build up that energy however to make that possible they also need to add magnets to make the particles curve around the path of the accelerator this comes with the problem that now every time the accelerating particles interact with a magnetic field and curved their trajectory they also lose energy as something called cyclotron radiation basically they release photons every time it happens and those photons carry away some of the energy to combat these losses physicists just make the accelerators bigger and bigger and bigger so what makes a wakefield accelerator better well the main thing is that they can accelerate particles a lot in the span of a couple of meters whereas a traditional accelerator would require kilometers for the same amount of acceleration if wakefield accelerators are so much more efficient why aren't they the standard that everyone uses well currently you need a decent sized regular accelerator or an aggressively powerful laser to run them to understand why let's jump in and see how they work fundamentally all the Wakefield accelerator is is a long tube filled with a metallic gas usually something like lithium Vapor there are two ways to actually turn this into an accelerator which as I mentioned are really big laser and smaller particle accelerator let's look at the lasers first for your driving laser you need one that can deliver a pulse that's very short but very powerful kind of like a light bullet when you fire that into the plasma cell in the name for the tube full of vapor the light has so much energy that it causes the gas to ionize and become plasma more importantly the pulse leaves a wake behind it as electrons and ions get pushed around by the sudden bursts of electromagnetic energy think of it like the wake of a boat where the path behind the boat is choppy with lots of little peaks and troughs in the water in this case rather than rough water some areas are very positive and some are very negative you may notice that those oscillations look similar to the pattern of charges in a normal particle accelerator the trick is to fire the thing you want to accelerate through the tube but just behind the light pulse if we use a bunch of electrons as our thing to be accelerated the area just behind the light pulse ends up very positive so the electrons are constantly being pulled towards it this accelerates the electron bunch to a good fraction of the speed of light very quickly as the electrons chase the light pulse the thing that really makes this process work is that the laser pulse loses energy to the wake which is then transferred to the electrons however as you can imagine timing is critical if the pulses are too close are too far apart this doesn't work properly and things don't accelerate this whole process when it does work is what's called self focusing the trailing bunch of electrons actually get packed together into a dense little packet as they're accelerated which is extra useful using a particle accelerator to drive these is similar but instead of using high-powered lasers they just send two bunches of particles one behind the other thanks to the energy handoff that the wakefield makes possible you can give all of the energy of the first Bunch to the trailing bunch giving it a huge speed boost so how much kick do these things really have as of now groups have been able to accelerate particles 9 Giga electron volts higher in only 1.2 meters worth of wakefield such as in the fasted one facility for comparison most line acts don't do that in a kilometer and that was only 30% energy transfer from the accelerating Bunch to the trailing bunch they're building a new facility that should be able to transfer up to 80% of the energy in only a single meter of accelerator and for me that's why Wakefield accelerators are so exciting on their own they can do a lot and will maybe replace the other accelerator types in the years to come but even now as little add-ons to current accelerators they can boost the energy significantly without taking up much space at all everyone's kind of getting on the Wakefield train now to CERN and many other national accelerator facilities around the world are all starting to work on their own Wakefield projects but I think the thing I find the most interesting about all of this is that it might be happening in space yeah you heard me right space accelerators let me explain when a star blows up in a supernova it goes without saying that there's some pretty impressive pressure waves emanating from that explosion we don't usually think about it but there's also extremely intense magnetic fields present as well the interaction of the magnetic fields and the plasma is called magneto hydrodynamics as the fields and plasma interact they're both bent and shifted around the fields develop these little Wiggles called alfvén waves which are how they release some of that tension you also have areas where the plasma is very dense in areas where it's less dense and all that turbidity you end up with areas that behave just like a Wakefield accelerator these sorts of waves and systems are everywhere - even streams of particles coming off of the Sun or boosted a bit by the Alphen waves in the sun's magnetic field it's part of the reason why the corona of the Sun is so unusually hot everything is getting a little extra boost cranking the temperature wait up and if that's possible with the fields from just our Sun imagine what the waves coming off something like a black hole merger would do either way the result would be extremely high energy cosmic rays especially ones made of elements that shouldn't otherwise be moving so quickly as it happens we do detect a large amount of cosmic rays with these aggressively high energies that can't be explained by other processes my personal favorite is called the oh my god particle the oh my god particle was detected back in 1991 and had an energy of 300 quintillion electron volts or 3 times 10 to the 20 electron volts the LHC for comparison reaches about eight times 10 to the 12 electron volts so eight orders of magnitude smaller it's about as much energy isn't a hundred mile per hour baseball but packed into the space of a single atom if it didn't hit you you'd probably have felt it no man made accelerator will ever reach close to that high I'm actually working with a friend to put together a cosmic ray detector so at some point we'll revisit cosmic rays so that we can see how we can detect various types if all goes well we should be able to pick up some rare particles like muons we probably won't detect any oh my god particles but we'd still be able to explore all sorts of cool phenomena the funny thing is that nature is and probably always will be the best particle accelerator so a lot can be learned about high-energy physics by simply pointing the right kind of telescope skyward so those are Wakefield accelerators an amazingly simple device that one day could mean desktop sized accelerators as powerful as the LHC just imagine the science we could do with something like that and with that I'll wrap up this video if you've enjoyed and want to see more be sure to subscribe and click the bell icon to get notifications when I post new videos I post a new video every Monday so be sure to check back for all new content if you want some awesome science themed merch or just want to support the show check out my store or consider becoming a patron as always thanks to my amazing patrons who helped make these videos possible that's all for now and I'll see you next time you

Channel: The Thought Emporium

Views: 174,225

Keywords: physics, collider, accelerator, accleration, gev, tev, lhc, particle acclerator, particle accelerator, tevtron, linca, linear accelerator, linac, cosmic ray, air shower, muon, oh my god particle, proton, wake, wakefield, supernova, black hole merger, black hole, sun, corona, alfven, magnetosonic, magnetohydrodynamics

Id: UZbXGDxMRCw

Length: 8min 55sec (535 seconds)

Published: Mon Feb 26 2018