In America, if you make fun out of president's favourite podcaster, you go to jail
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if you have an antenna with impedance of, say, 200 ohms, then you need to match it to transmitter impedance of 50 ohms, or else most of power output from transmitter would be bounced back and will damage output stage of amplifier. because on receive currents are tiny, you can wing it by just using it without any match and connecting it directly
transformers are not the only way to do this, and some other circuits can be used instead. if you take a transformer with 1:2 winding ratio, then if on one side current is 1 and voltage is 1, then on the other current will be 0.5 and voltage 2, which means that impedance increases 4x. in EFHW, it's 1:7 winding ratio and impedance ratio is 49x, which works for end-feeding a half-wave dipole, just as expected (from 50 ohm to ~2500 ohm). that transformer is a limitation on power usable in this antenna and main reason to use this type of antenna is mechanical
most importantly, transformers work nicely only if you have real impedances, so your antenna has to be resonant anyway. l- or pi-network tuner will also handle complex impedances so doublet or random wire will work nicely with it, as long as you can accept weight and losses in tuner
how compact and what do you want to do with it? if it's for receive only, the most compact you can get is ferrite rod antenna, but it's very different from usual wire antennas used for transmission. if using wire antennas, random wire would be fine
it depends on whether you want to transmit or not. if not, you can just use random wire antenna
random wire antenna is exactly what it says on the tin - length of random wire strung up as high as you can, as long as you can make it work. the other part is ground, where you might want to lay some lengths of wire and connect them in a single point, to act as radio ground. it won't have right impedance (probably 50 ohm) but for receive, this is ok - it'll be probably usable, and you can amplify signal without penalty because amplifier noise will be much smaller than atmospheric noise already present. the amount of power bouncing around is tiny and can't damage anything
if you want to transmit, you'll need more elaborate antenna. what you can use depends on whether do you have a tuner like neidu3 describes or not. if you do, common choice is doublet which is a specific length of wire connected to tuner with a 400-ohm parallel line. if you don't, common choice is halfwave dipole which is halfwave long, and put as high as you can get, either vertical or horizontal, but for practical reasons mostly horizontal, or monopole, that is quarterwave long, but requires lots of wire on ground to act as radio ground. you can make them shorter using coils, but this makes bandwidth narrower. in any case, it'll be need to be tuned to your band in question, for which you need a tool like nanoVNA. tuner also narrows your bandwidth, but you can retune it so it doesn't matter that much. (it'c called instantaneous bandwidth)
wait, i thought these turbines were already backordered because of them? not only regular gas turbines but also these converted ones. gas turbine is gas turbine
this is on top of power transformer shortage (which are always backordered, but were backordered before 2022, then ukrainians started buying more because their own got bombed, then techbros made backorders bigger)
238Pu is made from 237Np, which is almost pure isotope recovered in spent fuel reprocessing, especially for weapons use. americans stopped doing that in one of their major sites in 1988, ran out of it in 1993 and bought it from russia ever since, but russians also stopped making this isotope because it's mostly weapons grade plutonium byproduct and they have enough of it. americans still do some reprocessing but not enough to meet NASA needs, but also they started ramping it up to some degree. i understand that 241Am will be used to cover this gap at like 5x greater isotope weight
slight clarification here
so i looked it up again and this plutonium was already declared surplus, and was slated for disposal for 25 years now. it's a part of 34 tons of plutonium that both russia and us each were supposed to dispose of, as agreed in a treaty. that disposal consists of using plutonium as fuel, because irradiating it in reactor for a long time makes it useless for weapons use. russians did their part, in part because they were using plutonium in their own power reactors for a long time, so they could just use existing infrastructure. americans didn't, and they wanted to contaminate it with something and store underground, but some people wanted to burn it in reactors as it should be, so they instead did nothing and they still have some of that plutonium in there. that contamination can be probably reversed so russians objected to it, and didn't like that americans did nothing either. this is why russians suspended this treaty in 2016 and formally withdrew this monday. therefore it was a fire sale then and it is a fire sale today
and the reason for why americans don't have infrastructure or expertise to use plutonium as fuel is at least partially another fire sale, which used up russian ex-weapons uranium for fuel in american powerplants and started five years prior (russia was flat broke in 2000). rosatom became significant fraction of nuclear fuel supply worldwide (until that ex-weapons uranium ran out), that pushed nuclear fuel prices down and guided management decisions against plutonium-based fuel in infinite wisdom that uranium will stay cheap forever (plutonium remains more expensive now, but it doesn't have to be the case forever). another big one was american policy against reprocessing spent fuel. couple of other countries have national energy utilities that have different priorities and do recycle their fuel in way that would be useful for the program above, weren't part of this program and continued to use plutonium for multiple reasons. americans could ask for technical assistance from french or japanese or other allied countries, or perhaps even pawn plutonium to them, but i guess that not-invented-here syndrome won
i don't know what kind of diplomatic win are they trying to get there, if any, considering that russians don't care about this treaty anymore and had more surplus plutonium anyway
i wonder if someone pointed that thing at tarpit already
wint @dril 29 Dec 2014 and another thing: im not mad. please dont put in the newspaper that i got mad.
long hand of casey newton (by proxy) outputs a weird hit piece on ed zitron in wired https://archive.is/chsCw so far bluesky in shambles with no other effects
so on top of that 1%-ish gallium (which stabilizes delta phase, the least dense one, that collapses under pressure to alpha, the most dense one, which allows slightly less compression to be used, and this means more compact weapons), which would need to be separated before that plutonium gets turned into MOX, i understand that most of american plutonium stockpiles are somewhere around 94% 239Pu, and some are 97%+. i guess they're selling the worst stuff, which would make little difference for reactors, and if there's anything that american military is good at, it's logistics. on production side, the very shortened story is that we start with uranium and irradiate it, which gives
238U (n,gamma) 239U (beta) 239Np (beta) 239Pu
and that's it. but it really is a bit more complicated, because first, nothing stops that just made plutonium from reacting further, so some of it will fission which means that it can't be recovered, but it also means more neutrons, which will also make some plutonium, so it's not all bad. but not all plutonium will fission, and so there's entire series of reactions:
239Pu (n,gamma) 240Pu (n,gamma) 241Pu (n,gamma) 242Pu (n,gamma) 243Pu
at this point reaction stops because 243Pu is very short-lived, and it decays into 243Am. at the same time, if neutrons react without leaving fuel pin, they won't be slowed down much, which means another reaction is possible (but much less likely):
242Pu (n,2n) 241Pu (n,2n) 240Pu (n,2n) 239Pu (n,2n) 238Pu
there's also 238U (n,2n) 237U (beta) 237Np (n,gamma) 238Np (beta) 238Pu
of these, 238Pu and 240Pu have unacceptably high neutron emission rate, which means that if there's too much of these nuclear weapon is likely to predetonate. because the most important use of plutonium in modern advanced thermonuclear weapons is in primary, this means that it could be so that entire weapon fails to function if there's too much of these contaminants (low-kt or even sub-kt yield instead of, say, 350kt). of these, 238Pu and 241Pu have short halflives, which means that plutonium containing these will heat up with considerable power. this can damage explosives bonded to it. 240Pu is additionally a radiation hazard because of neutrons emitted, but it's only really relevant for submarine crews. this is why these weapons use the better 97%+ grade plutonium, and additionally some of that 97% grade was made in order to blend with some older, worse quality stocks
there's remarkably few parameters that can be used in order to steer these reactions in the way we want. about the only relevant one here would be neutron temperature, which is really chosen at reactor design stage and increasing it means that neutron capture is less likely. this makes fission more likely, more neutrons are present and more plutonium can be formed. this also turns reactor into fast reactor which are notoriously hard to build and iirc only russia and india operate large fast reactors today. short of that, about the only way to prevent 239Pu from reacting further is to take it out of there, which means low burnup and only tiny amounts can be recovered per run. from what i understand, the choice of 94%-ish 239Pu content is end effect of massive optimization problem focused on how to make a pit at the lowest price. this includes all the (expensive, slightly dangerous) labour it takes in reprocessing fuel and how required pit mass increases with lower quality plutonium
little of that matters when running a powerplant. some isotopes being neutron emitters are actually an advantage because it makes startup smoother. the longer fuel stays in reactor the less fissile plutonium there is as a result, and the more advanced reactors allowing higher burnups make plutonium recovery less attractive, or, in other words, most of benefit of recovering plutonium in order to put it in new fuel can be realized just by leaving fuel in reactor for longer time in the first place. in regular light water reactor, steady state develops where plutonium is formed as fast as it is consumed, and it accounts for about third of energy released when that steady state sets in. this also means that about third of fissile uranium can be replaced by fissile plutonium with no modifications to reactor
on top of weapons use, some countries do reprocessing anyway as a matter of policy as a hedge against future shortages of uranium. some of these schemes require fast reactors which can burn these isotopes useless in regular reactor and make fresh, weapons grade almost pure 239Pu, which limits countries that can make it work, by diplomatic means, only to already established nuclear powers, and labour costs needed for its operation limit it to currently only india and russia, and formerly france. this is because at any burnup, in best case plutonium can be only separated once from light water reactor fuel and used in light water reactor. after that, plutonium quality is too low to be useful this way
in comparison to reactor grade plutonium, weapons grade plutonium would allow to make more fuel per kg of this material, but also it would be astronomically expensive compared to regular stuff, which is already unprofitable for power generation in countries with western labour costs, unless it's a fire sale. the second problem is that if more than this 1/3 of fissile isotopes in fresh fuel is plutonium, then generally reactors would need recertification or maybe completely new design, because plutonium gives less delayed neutrons which are critical for smooth control of reactor power. this is, mind you, in context of country that practically stopped building new nuclear powerplants. if small reactors are on the table, then these naturally need higher amount of fissile isotopes, like 20-30%, and something tells me people involved would like to try this
another thing to note here is that there's an old american policy in place that forbids (domestic) plutonium recovery for alleged (international) nonproliferation reasons. i don't believe this is the case, it makes zero sense, and instead i think that nuclear industry wanted a way out of that money pit without state backing, because plutonium recovery and reuse for power generation is more expensive than just buying more uranium, sustainability of this energy source and volume needed for nuclear waste be damned. they could get away with this because military weapons grade plutonium stockpiles were assessed as sufficient. now they're pawning heirloom nukes to monorail salesmen instead
every batch of plutonium is made mostly out of Pu-239 that's just how plutonium works. it can't be separated into isotopes in any meaningful amounts so any batch of plutonium is also a mix of a couple of isotopes. reactor grade might be something like 55% Pu-239 plus say 12% also fissile Pu-241 with the rest being nonfissile Pu-240, Pu-242 and Pu-238 in that order. the newer reactor and fuel pin design, the higher burnup and the less fissile isotopes will be present at the end of the cycle. even in purely uranium fueled reactor about third of energy at the end of the fuel cycle comes from plutonium bred in the same fuel pin. i can elaborate on that if you want to
this shouldn't be surprising if you paid any amount of attention https://en.wikipedia.org/wiki/Pravda_network https://www.france24.com/en/live-news/20250310-russian-disinformation-infects-ai-chatbots-researchers-warn
i don't think so, it's like megatons to megawatts but stupider, instead of using up uranium from adversary they want to use up their own plutonium, while also having policies against spent fuel reprocessing (for alleged nonproliferation reasons, which is patently bullshit, power generation was straight up cheaper this way because new uranium is cheaper than reprocessing and use of mox. some other countries (at minimum ru, fr, in, pk, jp, cn, il) do reprocessing as a matter of national security/energy independence/hedge against future shortages of uranium). also this requires recertification of reactors for mox use, which won't always work or else only part of uranium can be replaced, and if it's for smr, then there's gonna be a lot of plutonium in there, and it all starts with handing plutonium to motherfucking sam altman, for only a slight chance of any positive results
i see it more as current administration ripping copper wiring from walls than anything else tbh
in my country it used to be like this for 50 years, you get flat rate per day, counted up to fractions of day, separately for accomodation and food + everything else. you only have to keep transportation tickets
behold, disruption
i don't mean beta-oxidation, it's just a series of separated normal reactions. i mean something like this: when first learning about ketones, you might learn about aldol condensation, which has enol as a nucleophile and another carbonyl as electrophile. at some other point you might learn about strecker reaction, which has iminium ion as electrophile and cyanide as nucleophile. but really, what you can do is mix and match, and you can pair enolizable ketone and iminium (mannich reaction) or carbonyl and cyanide (cyanohydrin formation) and then generalize, for example you don't need strictly ketone for mannich, you can use any electron rich conjugated system like malonate or nitroalkane anion (henry reaction) or phenol or indole. to figure this out you need to study mechanisms. these last two are usually treated as variants of friedel-crafts reaction, but really categories like this are fake
and to get that right, you need to know how these reactive intermediates look like, how reactive they are, what influences their stability which means that ochem starts with discussion of carbocations, carboanions, radicals, their shapes and orbitals involved, hyperconjugation, solvent effects and the like. and then first reactions taught are sn1/sn2, because these showcase these fundamentals nicely, and from there, it's about introduction of more compound classes
we only had synthons introduced during lecture at around 4th year, and only for ochem path, it's not doing a lot at that point and imo would have much more impact right after ochem intro course
it's lowkey crazy how fast has she adapted to being a conservative grifter