5 ms·
Highest-Voltage Electron Gun
- swayvil 2y agoDo electrons get weird under high acceleration?
- analog31 2y agoNot particularly weird, but they radiate energy as they accelerate. You don't want to be in the same room as this thing when it's running.
- swayvil 2y agoWhat kind of energy?
- mgc_mgc 2y agoPhotons. https://en.wikipedia.org/wiki/Bremsstrahlung https://en.wikipedia.org/wiki/Bremsstrahlung
- analog31 2y agoIndeed, and this is a reason why, traditionally, electrons are studied using linear accelerators, rather than rings. It was the main purpose of Stanford Linear Accelerator (SLAC) as I understand it. When electrons are accelerated in rings, it's usually because you want to do something with the radiation, and not the electrons.
- Loughla 2y agoWhat would that do to you? Sunburn?
- deleted 2y ago[deleted]
- swayvil 2y agoI'm figuring the photonic stuff covers all electromagnetic. So sunburn, microwave, cancer. Lots of options.
- klodolph 2y agoOrdinary consumer equipment already accelerates electrons enough to produce X-rays. Or at least, it did, back in the CRT era. This accelerator is presumably more powerful than consumer entertainment hardware.
- guepe 2y agoThat reminds me of a question I was asking myself: instead of using rare gas for ion thrusters… why not ejecting very high velocity electrons ? Their mass is much, much smaller than any atom, but why wouldn’t that lead to a thrust ? Possibly without limit except power - no limit on a “tank”?
- hansvm 2y agoWhere do the extra electrons come from?
- sbdhzjd 2y agoThe thruster would quickly die out once the static electricity on the vessel created an energy well that matches the energy of the electrons thrust. Instead use a powerful laser. Light carries momentum without the need to preserve charge.
- guepe 2y agoAh! That “well” is exactly what I couldn’t understand from ion thrusters, where they shed electrons as they expulsé ionized gas. All I could find was “to keep the same charge”, but since there is no absolute ground, what’s the problem? You just explained it :)
- sbdhzjd 2y agoNp. I remember first coming to that realization. Fun thought experiment: what happens to a beta emitter in outer space?
- addaon 2y ago> why not ejecting very high velocity electrons ? This works, initially. Now, you have to balance the charge on your space craft, or else you won’t be able to eject any more electrons. If you balance this charge by ejecting protons, you have a hydrogen thruster. If you balance this charge by ejecting positrons, you have a photon thruster (in the far field). The former is still “tank” limited. The latter requires high energy to get any useful impulse.
- Workaccount2 2y agoHow could you drop the ball so hard that you write an article titled "highest voltage electron gun" and not even state once what the voltage is in the article? It's like writing an article about "the world's tallest tower" and just saying "it goes really high!" to convey its height.
- Someone 2y agoFTA: “Read the complete story at the BNL website.” That article (https://www.bnl.gov/newsroom/news.php?a=222117 https://www.bnl.gov/newsroom/news.php?a=222117) has the answer: “In commissioning tests in a basement lab at SBU, ramping up the voltage to the goal of 350 kilovolts took about 23 hours. Then the gun operated maintenance free for six months” The goal isn’t to get a high voltage, though; it’s to get fast electrons. for that, the article does say what this machine does: “The powerful gun speeds up the velocity of electrons to 80 percent the speed of light” By the way, 350kV does not look enormous compared to cathode ray tubes. https://en.wikipedia.org/wiki/Cathode-ray_tube#Body https://en.wikipedia.org/wiki/Cathode-ray_tube#Body: “The glass formulation determines the highest possible anode voltage and hence the maximum possible CRT screen size. For color, maximum voltages are often 24–32 kV, while for monochrome it is usually 21 or 24.5 kV”.
- MengerSponge 2y ago10x doesn't look enormous?
- fnordpiglet 2y ago350kv is definitely not enormous. Marx generators can make 100MV potentials and high energy particle accelerators can make fields in the gigavolt and teravolt ranges. The headline is just a bit ludicrous. (IANAP)
- sroussey 2y agoterrestrial gamma-ray flashes in the upper atmosphere can have energies of up to 20 million electronvolts
- perihelions 2y agoPrimary source is https://www.bnl.gov/newsroom/news.php?a=222117 https://www.bnl.gov/newsroom/news.php?a=222117 ("High-Voltage Gun Accelerates Electrons from Zero to 80 … Percent the Speed of Light") This one's the same article, but in excerpted form.
- dang 2y agoChanged from https://news.stonybrook.edu/university/sbu-helping-bnl-develop-the-worlds-highest-voltage-electron-gun/ https://news.stonybrook.edu/university/sbu-helping-bnl-devel... above. Thanks!
- ahartmetz 2y agoIn case anyone wonders what's the big deal about this: As someone who knows a liiittle bit about collider physics, I think a relatively clean, relatively high energy electron gun has the advantage of reducing the "emittance" of the beam, i.e. creating a beam whose particles have speeds and movement directions very close together. Starting with a low emittance beam means it's easier to end up with a low emittance beam, though AFAIU starting with a very clean beam is not a hard requirement - there are "conditioning" methods, some of which lose a fraction of the particles (not ideal).