The TAE concept I find really neat as an engineer, but the theoreticians I discussed it with basically said it's based on old concepts and they wouldn't hold their breath for dramatic improvements in containment. We should know fairly soon as they continue to scale though.
I don't get the general fusion concept, seems like you'd have massive bremsstrahlung losses. Maybe if they made a molten salt fission-fusion hybrid with the concept, but just seems sort of bizarre to me. The lockheed concept looks like total rubbish, it's a physics mishmash but engineering wise putting superconductors so close to the neutronic region means it would last all of 2 seconds in reality.
For "mainstream" fusion work began in earnest around the 50s. The 1938 work by Kantrowitz is still interesting; he had rudimentary magnetic containment with RF heating, just off by a magnitude or so. Most aren't aware of this work and it had little impact, so it's more or less an anecdote.
I'm not a theoretician, but it is well known that reactor designs can be inmproved dramatically with higher fields. The MIT arc reactor concept capitalizes on this, but it's arguable the engineering effort required has been glossed over. For one, you can't make cables long enough for the central magnet and therefore need splices internally which are very difficult to pull off with HT cable. Not insurmountable but would take some R&D effort.
I had asked a theoretician if we had unlimited computational resources could we model a working tokamak reactor, and he kind of laughed and said no, not yet.
If ITER had been fully funded it's entirely possible we could have a breakeven reactor, I do agree with the "funding never" chart someone else linked. I think the estimates are very low and optimistic, the engineering realities are always more problematic in fusion. Very unforgiving environment. I'm not sure with a tokamak such as ITER if it will ever be *economical* however, due mainly to the MIT tech review article I linked. A 20 billion dollar fusion reactor will cost far more in maintenance and upkeep than a 1 billion dollar fission reactor that produces the same power. This appears to be a fundamental issue with tokamaks using the D-T cycle.
I used to work in fusion, the engineering problems that need to be overcome before we have a working commercial reactor are tremendous. Also I tend to believe with some older critics that a tokamak will never be commercially viable:
Computer modeling has been a tremendous help, but we do not have the capability to simulate a working tokamak reactor yet. We don't even have a complete understanding of plasma physics, for example modeling disruptions and ELMs in reactors can't yet be done to the best of my knowledge. Simulation generally needs very complex monte carlo models that simulate chemistry and nuclear interactions, magnetohydrodynamics (electric-magnetic "fluids"), etc.
Better magnets help shrink the size and may help reach new operational modes more easily, but this field is unbelievably slow. The current state of the art is Nb3Sn, and the material was discovered over 50 years ago. To get good magnets made from HT superconductors you're looking at a few more decades. This is one issue with the MIT arc design, the magnets required can't quite be made yet by the looks of it. Also the cables are tremendously expensive, Nb3Sn roughly $1k/m
Better materials help, but the radiation coming from a nuclear fusion reactor cannot be simulated offline to help develop new materials. Think an order of magnitude more nuetron flux than fission, but also proton bombardment and helium bubbles forming. Using a spallation neutron source may get the neutron flux, but not the proton flux etc. Best way is to try out new materials in the reactor...
We're nearing 100 years of trying to make fusion work, it's just the most difficult problem humanity has ever tried to solve. The first real attempt at building a fusion reactor was in 1938 by Kantrowitz. I am excited by these new companies in the US and UK that are going back the the drawing board and throwing out the tokamak, but I still don't see it happening in my lifetime.
As an engineer I once pressurized an assembly that had a seal created by a kapton tube, was leaking to the point bubbles were trickling out when submerged. Kept tightening, troubleshooting, etc to no avail. I was using helium just because we had a line supply where I was testing; when I switched to nitrogen it made a perfect seal.
I found it hard to believe so crunched the numbers. It's correct but with a small caveat, 22.4 MJ is for all 120 bar discharged. A 50 bar drop from 120 bar to 70 bar is ~8.4 MJ.
For those interested:
E = (P_1 * V_1) / (gamma - 1) * [1 - (P_0/P_1)^( (gamma - 1) / gamma))] P_1 is pressurized gas P_0 discharge atmosphere pressure gamma for air is 1.4 (get more energy with CO2 etc) E in joules, assumes reversible isotropic
For context 8.4 MJ is ~6-7 compressed gas cylinders.
Also particle shape matters, many nanoparticles that are spherical are benign, but when "sharp" they puncture cell walls and resist encapsulation resulting in a pile of dead cells trying to remove the particle.
I used to think so as well, particularly despised him with the constant spraying everyone with champagne while grinning like an idiot that seemed to be constantly on TV. A friend convinced me to read his book "Losing My Virginity", really made me admire him. Very adventurous businessman who understands life and seems to genuinely care about his employees.
But you're fairly spot on about the change I think. His book that came out last year as a follow up was an absolute pain to finish - all politics along with his views and opinions on extremely complex issues stated as fact. I get the sense he's seeing people like Musk innovating and realizing he hasn't truly made a transformational mark on society. It's eating at him so he's getting involved in space, hyperloop, etc. Not his strong suit, but hey if he succeeds great.
If you watch the videos it's not "blast" proof, and they never tested it for any mechanical strength in the videos. However the intense radiation as from a nuclear blast or laser is completely absorbed, with one scientist quoted as saying the depth of damage appears to be exactly the minimum needed to accommodate the laser, nothing is transmitted further. The material then expands to a low thermal conductive carbon foam which is just warm to the touch immediately after an oxy-acetylene torch is turned off. All the material scientists were certainly intrigued.
It's been >10 years since my courses, but I believe I read that Schrodinger himself felt uncomfortable assigning the wave formula to what was supposed to be a probability function - but it was the only thing that mathematically made sense even if it was physically nuts. A lot of it was observation done in the old way, but with some mathematical derivation that didn't necessarily elucidate what's actually occuring at a fundamental level. You have to just believe in probability wave functions without understanding why that is.
I don't recall which book it was (I think "Becoming Steve Jobs"), but I found it interesting that while everyone essentially agreed he was tough to work for he also had a lot of compassion to go with the assholery. One striking passage said everyone involved in the Macintosh development looked back at it as some of the best years of their lives despite how grueling it was. I think personally why people tend to admire him despite his negative traits was the overwhelming fact that he cared and didn't stand for mediocrity.
Yep, it's a big problem. Few things to look out for:
1) As you mentioned, many same day reviews. 2) Clicking on reviewer's page shows they post many reviews the same day, or cater towards a specific product or company. 3) Review text mentions another product. For example sellers will sell a cheap USB stick (perhaps even losing $) to get lots of legit reviews, then change picture and title. 4) Lots of copy-paste text from bots.
The most egregious? These same sellers will use the same tactics to down vote competitors. I find myself purchasing at target and walmart or local stores more frequently, but some times resort to buy and return.
From "The Young Man in Business", Edward W. Bok (c. 1896)
"If he be wise he will entirely avoid the use of liquors. If the question of harm done by intoxicating liquor is an open one, the question of the actual good derived from it is not."
These guys should learn from Ford who doubled pay and reduced hours -- you make your workers happy they will come around and work harder for the company, less turnover, less sick days, etc.
Another factor is they can't use swipe or similar keyboards to type (pinyin keyboards you have to construct and often choose a character from a few possibilities), so not looking at the screen isn't an option. As a result while walking, driving, or otherwise multitasking audio is a must. My limited trips there I was astonished at the walk and drive usage of phones.
They aren't too hard to understand, basically you have a plasma (soup of electrons and nuclei) and fire a laser down the axis. The laser's electric field pushes particles outward momentarily, and after the laser is gone they start collapsing towards where they originally were, creating a "wave" that progresses down the axis of the plasma. By injecting electrons at the correct moment you can accelerate them by "surfing" this wave, exactly as a human surfer on an ocean wave.
You can vary the wave's speed arbitrarily and even faster than the speed of light if you wish (some get lost here, but think of pointing a laser pointer at the moon in a sweeping motion - the dot might go faster than light but no information transfer is occurring). This along with the massive electric fields means your accelerations gradients are much larger than the typical cavity accelerators, and can even achieve giga-electronvolt energies in cm. Neat technology that can put high energy labs on tabletops potentially.
I'm not an expert by any means though, just my understanding. Based on the summary I believe this group showed by replacing the laser with a proton beam you can still demonstrate the same effect, but I'll have to read it more carefully to get a better idea.
Slashdot Mirror
I'm very excited for the SpaceX Starlink for this reason. I would give them $400/mo just to finally get out of Comcast's monopoly.
The TAE concept I find really neat as an engineer, but the theoreticians I discussed it with basically said it's based on old concepts and they wouldn't hold their breath for dramatic improvements in containment. We should know fairly soon as they continue to scale though.
I don't get the general fusion concept, seems like you'd have massive bremsstrahlung losses. Maybe if they made a molten salt fission-fusion hybrid with the concept, but just seems sort of bizarre to me. The lockheed concept looks like total rubbish, it's a physics mishmash but engineering wise putting superconductors so close to the neutronic region means it would last all of 2 seconds in reality.
For "mainstream" fusion work began in earnest around the 50s. The 1938 work by Kantrowitz is still interesting; he had rudimentary magnetic containment with RF heating, just off by a magnitude or so. Most aren't aware of this work and it had little impact, so it's more or less an anecdote.
I'm not a theoretician, but it is well known that reactor designs can be inmproved dramatically with higher fields. The MIT arc reactor concept capitalizes on this, but it's arguable the engineering effort required has been glossed over. For one, you can't make cables long enough for the central magnet and therefore need splices internally which are very difficult to pull off with HT cable. Not insurmountable but would take some R&D effort.
I had asked a theoretician if we had unlimited computational resources could we model a working tokamak reactor, and he kind of laughed and said no, not yet.
If ITER had been fully funded it's entirely possible we could have a breakeven reactor, I do agree with the "funding never" chart someone else linked. I think the estimates are very low and optimistic, the engineering realities are always more problematic in fusion. Very unforgiving environment. I'm not sure with a tokamak such as ITER if it will ever be *economical* however, due mainly to the MIT tech review article I linked. A 20 billion dollar fusion reactor will cost far more in maintenance and upkeep than a 1 billion dollar fission reactor that produces the same power. This appears to be a fundamental issue with tokamaks using the D-T cycle.
I used to work in fusion, the engineering problems that need to be overcome before we have a working commercial reactor are tremendous. Also I tend to believe with some older critics that a tokamak will never be commercially viable:
http://www.askmar.com/Robert%2...
Computer modeling has been a tremendous help, but we do not have the capability to simulate a working tokamak reactor yet. We don't even have a complete understanding of plasma physics, for example modeling disruptions and ELMs in reactors can't yet be done to the best of my knowledge. Simulation generally needs very complex monte carlo models that simulate chemistry and nuclear interactions, magnetohydrodynamics (electric-magnetic "fluids"), etc.
Better magnets help shrink the size and may help reach new operational modes more easily, but this field is unbelievably slow. The current state of the art is Nb3Sn, and the material was discovered over 50 years ago. To get good magnets made from HT superconductors you're looking at a few more decades. This is one issue with the MIT arc design, the magnets required can't quite be made yet by the looks of it. Also the cables are tremendously expensive, Nb3Sn roughly $1k/m
Better materials help, but the radiation coming from a nuclear fusion reactor cannot be simulated offline to help develop new materials. Think an order of magnitude more nuetron flux than fission, but also proton bombardment and helium bubbles forming. Using a spallation neutron source may get the neutron flux, but not the proton flux etc. Best way is to try out new materials in the reactor...
We're nearing 100 years of trying to make fusion work, it's just the most difficult problem humanity has ever tried to solve. The first real attempt at building a fusion reactor was in 1938 by Kantrowitz. I am excited by these new companies in the US and UK that are going back the the drawing board and throwing out the tokamak, but I still don't see it happening in my lifetime.
Don't think we won't!
As an engineer I once pressurized an assembly that had a seal created by a kapton tube, was leaking to the point bubbles were trickling out when submerged. Kept tightening, troubleshooting, etc to no avail. I was using helium just because we had a line supply where I was testing; when I switched to nitrogen it made a perfect seal.
I found it hard to believe so crunched the numbers. It's correct but with a small caveat, 22.4 MJ is for all 120 bar discharged. A 50 bar drop from 120 bar to 70 bar is ~8.4 MJ.
For those interested:
E = (P_1 * V_1) / (gamma - 1) * [1 - (P_0/P_1)^( (gamma - 1) / gamma))]
P_1 is pressurized gas
P_0 discharge atmosphere pressure
gamma for air is 1.4 (get more energy with CO2 etc)
E in joules, assumes reversible isotropic
For context 8.4 MJ is ~6-7 compressed gas cylinders.
Also particle shape matters, many nanoparticles that are spherical are benign, but when "sharp" they puncture cell walls and resist encapsulation resulting in a pile of dead cells trying to remove the particle.
I used to think so as well, particularly despised him with the constant spraying everyone with champagne while grinning like an idiot that seemed to be constantly on TV. A friend convinced me to read his book "Losing My Virginity", really made me admire him. Very adventurous businessman who understands life and seems to genuinely care about his employees.
But you're fairly spot on about the change I think. His book that came out last year as a follow up was an absolute pain to finish - all politics along with his views and opinions on extremely complex issues stated as fact. I get the sense he's seeing people like Musk innovating and realizing he hasn't truly made a transformational mark on society. It's eating at him so he's getting involved in space, hyperloop, etc. Not his strong suit, but hey if he succeeds great.
Laughed out loud, wish I had mod points today.
Fair enough. I'm more on the investing = gambling side of things.
>> Heck, even if they successfully build one, the company will fail if someone else builds a better one, or builds a similar one sooner.
With this mentality I don't think you'd be comfortable investing in any company.
A great book about how patents boosted civilization:
https://www.amazon.com/Most-Po...
If you watch the videos it's not "blast" proof, and they never tested it for any mechanical strength in the videos. However the intense radiation as from a nuclear blast or laser is completely absorbed, with one scientist quoted as saying the depth of damage appears to be exactly the minimum needed to accommodate the laser, nothing is transmitted further. The material then expands to a low thermal conductive carbon foam which is just warm to the touch immediately after an oxy-acetylene torch is turned off. All the material scientists were certainly intrigued.
World's most expensive tea for sure.
It's been >10 years since my courses, but I believe I read that Schrodinger himself felt uncomfortable assigning the wave formula to what was supposed to be a probability function - but it was the only thing that mathematically made sense even if it was physically nuts. A lot of it was observation done in the old way, but with some mathematical derivation that didn't necessarily elucidate what's actually occuring at a fundamental level. You have to just believe in probability wave functions without understanding why that is.
I don't recall which book it was (I think "Becoming Steve Jobs"), but I found it interesting that while everyone essentially agreed he was tough to work for he also had a lot of compassion to go with the assholery. One striking passage said everyone involved in the Macintosh development looked back at it as some of the best years of their lives despite how grueling it was. I think personally why people tend to admire him despite his negative traits was the overwhelming fact that he cared and didn't stand for mediocrity.
Yep, it's a big problem. Few things to look out for:
1) As you mentioned, many same day reviews.
2) Clicking on reviewer's page shows they post many reviews the same day, or cater towards a specific product or company.
3) Review text mentions another product. For example sellers will sell a cheap USB stick (perhaps even losing $) to get lots of legit reviews, then change picture and title.
4) Lots of copy-paste text from bots.
The most egregious? These same sellers will use the same tactics to down vote competitors. I find myself purchasing at target and walmart or local stores more frequently, but some times resort to buy and return.
From "The Young Man in Business", Edward W. Bok (c. 1896)
"If he be wise he will entirely avoid the use of liquors. If the
question of harm done by intoxicating liquor is an open one, the
question of the actual good derived from it is not."
No need to be alarmist. Our landfills are future mines.
These guys should learn from Ford who doubled pay and reduced hours -- you make your workers happy they will come around and work harder for the company, less turnover, less sick days, etc.
Another factor is they can't use swipe or similar keyboards to type (pinyin keyboards you have to construct and often choose a character from a few possibilities), so not looking at the screen isn't an option. As a result while walking, driving, or otherwise multitasking audio is a must. My limited trips there I was astonished at the walk and drive usage of phones.
Haha, we won't be able to match the energy of particles hitting the upper atmosphere for millenia (if ever). For example check out :
https://en.wikipedia.org/wiki/...
Would be pretty slick, probably even a compact x-ray laser with a good undulator...
They aren't too hard to understand, basically you have a plasma (soup of electrons and nuclei) and fire a laser down the axis. The laser's electric field pushes particles outward momentarily, and after the laser is gone they start collapsing towards where they originally were, creating a "wave" that progresses down the axis of the plasma. By injecting electrons at the correct moment you can accelerate them by "surfing" this wave, exactly as a human surfer on an ocean wave.
You can vary the wave's speed arbitrarily and even faster than the speed of light if you wish (some get lost here, but think of pointing a laser pointer at the moon in a sweeping motion - the dot might go faster than light but no information transfer is occurring). This along with the massive electric fields means your accelerations gradients are much larger than the typical cavity accelerators, and can even achieve giga-electronvolt energies in cm. Neat technology that can put high energy labs on tabletops potentially.
I'm not an expert by any means though, just my understanding. Based on the summary I believe this group showed by replacing the laser with a proton beam you can still demonstrate the same effect, but I'll have to read it more carefully to get a better idea.