Author Topic: Metallic Hydrogen is real!  (Read 13211 times)

Offline DMeader

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Re: Metallic Hydrogen is real!
« Reply #40 on: 11/09/2016 04:00 PM »
With metallic hydrogen, the atoms need be broken out of the metallic matrix, but that probably takes a lot less energy.

Once that happens, aren't the individual atoms going to want to immediately revert to the H-H configuration (covalent bond) with commensurate release of energy?

Offline Proponent

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Re: Metallic Hydrogen is real!
« Reply #41 on: 11/09/2016 05:23 PM »
With metallic hydrogen, the atoms need be broken out of the metallic matrix, but that probably takes a lot less energy.

Once that happens, aren't the individual atoms going to want to immediately revert to the H-H configuration (covalent bond) with commensurate release of energy?

No doubt, and, rereading the article and clicking through the links, the idea seems to be to rely on that energy alone, not bothering with the oxygen.

An Isp of 1700 s corresponds to an effective exhaust velocity of about 17 km/s.  For getting to LEO that's actually too high, if the objective is to minimize the amount of metallic hydrogen.  It might be optimal to add a cheap working fluid, ideally a monatomic one.  That would have the added advantage of keeping the temperature down.
« Last Edit: 11/09/2016 06:32 PM by Proponent »

Offline IainMcClatchie

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Re: Metallic Hydrogen is real!
« Reply #42 on: 11/09/2016 05:59 PM »
Metallic deuterium would allow self-detonating fusion devices. Friedwardt Winterberg has a design for a non-fission triggered D-T device (it's in one of his papers on viXra, since the arXiv wouldn't allow it.) He used standard chemical explosives in a rather complicated process. Such explosives pack the equivalent of ~350 s Isp. An implosion device made of solid metallic deuterium wouldn't need high explosives, since it would pack ~x10 the energy or so. And it'd be fusion fuel. Just squirt some tritium into the very centre.

Alternatively wrap lithium deuteride in a metallic deuterium magnetic compression target.

Also, superconducting rings of metallic hydrogen could be launched via a linear accelerator to be mass-beam pellets to push spacecraft. Ramming into a magnetic field around the vehicle at high speed would probably cause the superconductivity to quench, blasting the ring into high speed hydrogen plasma.

This post is the best piece of hard Sci-Fi I've read this year.

Offline qraal

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Re: Metallic Hydrogen is real!
« Reply #43 on: 11/09/2016 07:54 PM »
Thank you.

Hard SF wise, the chief take-away line is that metallic hydrogen is achieved. Everything else is just engineering.

Metallic deuterium would allow self-detonating fusion devices. Friedwardt Winterberg has a design for a non-fission triggered D-T device (it's in one of his papers on viXra, since the arXiv wouldn't allow it.) He used standard chemical explosives in a rather complicated process. Such explosives pack the equivalent of ~350 s Isp. An implosion device made of solid metallic deuterium wouldn't need high explosives, since it would pack ~x10 the energy or so. And it'd be fusion fuel. Just squirt some tritium into the very centre.

Alternatively wrap lithium deuteride in a metallic deuterium magnetic compression target.

Also, superconducting rings of metallic hydrogen could be launched via a linear accelerator to be mass-beam pellets to push spacecraft. Ramming into a magnetic field around the vehicle at high speed would probably cause the superconductivity to quench, blasting the ring into high speed hydrogen plasma.

This post is the best piece of hard Sci-Fi I've read this year.

Offline Sam Ho

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Re: Metallic Hydrogen is real!
« Reply #44 on: 11/09/2016 08:40 PM »
With metallic hydrogen, the atoms need be broken out of the metallic matrix, but that probably takes a lot less energy.

Once that happens, aren't the individual atoms going to want to immediately revert to the H-H configuration (covalent bond) with commensurate release of energy?

No doubt, and, rereading the article and clicking through the links, the idea seems to be to rely on that energy alone, not bothering with the oxygen.

An Isp of 1700 s corresponds to an effective exhaust velocity of about 17 km/s.  For getting to LEO that's actually too high, if the objective is to minimize the amount of metallic hydrogen.  It might be optimal to add a cheap working fluid, ideally a monatomic one.  That would have the added advantage of keeping the temperature down.
The paper said that a monopropellant would have an Isp of 1700s and a temperature of around 7000K.  Hydrogen diluent to take the temperature down to 3500K-3800K would result in an Isp of 1030-1120s, and water diluent would have an Isp of 460-540s.

http://nrs.harvard.edu/urn-3:HUL.InstRepos:9569212

Online Stormbringer

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Re: Metallic Hydrogen is real!
« Reply #45 on: 11/10/2016 01:37 AM »
Metallic deuterium would allow self-detonating fusion devices.
not sure that that is a good thing given human inhumanity to their fellow humans in large numbers, --despite the good non destructive (non-murdilating) uses such things would have.
When antigravity is outlawed only outlaws will have antigravity.

Offline qraal

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Re: Metallic Hydrogen is real!
« Reply #46 on: 11/11/2016 11:47 AM »
Nuclear weapons generally make co-belligerents nervous. Conventional weapons less so.

Metallic deuterium would allow self-detonating fusion devices.
not sure that that is a good thing given human inhumanity to their fellow humans in large numbers, --despite the good non destructive (non-murdilating) uses such things would have.

Offline Star One

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Metallic Hydrogen is real!
« Reply #47 on: 01/26/2017 10:06 PM »
An update including a picture of the sample they have produced.

http://www.sciencealert.com/hydrogen-has-been-turned-into-a-metal-for-the-first-time-ever

And here's the paper published in Science.

Quote
Abstract

Producing metallic hydrogen has been a great challenge to condensed matter physics. Metallic hydrogen may be a room temperature superconductor and metastable when the pressure is released and could have an important impact on energy and rocketry. We have studied solid molecular hydrogen under pressure at low temperatures. At a pressure of 495 GPa hydrogen becomes metallic with reflectivity as high as 0.91. We fit the reflectance using a Drude free electron model to determine the plasma frequency of 32.5 2.1 eV at T = 5.5 K, with a corresponding electron carrier density of 7.7 1.1 1023 particles/cm3, consistent with theoretical estimates of the atomic density. The properties are those of an atomic metal. We have produced the Wigner-Huntington dissociative transition to atomic metallic hydrogen in the laboratory.

http://science.sciencemag.org/content/early/2017/01/25/science.aal1579?

More in this article.

Metallic hydrogen created in diamond vise

Quote
In 1935 a pair of physicists predicted that if the pressure of hydrogen were raised to about 25 times that of atmospheric pressure, it would turn into a solid metal. Experimentalists ever since have tried and failed to spot this transition, even after raising the pressure of hydrogen to millions of times atmospheric pressure. Now, the transition to solid metallic hydrogen may have been reached. Physicists in the United States say that by crushing a tiny amount of hydrogen between the tips of two flat-tipped diamonds at cryogenic temperatures they've raised the pressure to nearly 5 million times atmospheric pressure, causing the hydrogen to reflect light like a metal. They still don't have evidence the pressurized hydrogen is a solid. But even the claim that it is metallic is highly controversial. Other high-pressure physicists question some of the procedures used in the new study, and say they need more proof before they'll concede that the 80-year quest is over.

http://science.sciencemag.org/content/355/6323/332
« Last Edit: 01/26/2017 10:14 PM by Star One »

Offline as58

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Re: Metallic Hydrogen is real!
« Reply #48 on: 01/26/2017 10:54 PM »
And because the research was published in Science, Nature tries to spoil the party: http://www.nature.com/news/physicists-doubt-bold-report-of-metallic-hydrogen-1.21379

Offline Star One

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Re: Metallic Hydrogen is real!
« Reply #49 on: 01/27/2017 06:21 AM »
And because the research was published in Science, Nature tries to spoil the party: http://www.nature.com/news/physicists-doubt-bold-report-of-metallic-hydrogen-1.21379

Well to be fair the Science in-depth article even in the abstract from it mentions doubts.

Offline john smith 19

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Re: Metallic Hydrogen is real!
« Reply #50 on: 01/27/2017 06:49 AM »
An update including a picture of the sample they have produced.

http://www.sciencealert.com/hydrogen-has-been-turned-into-a-metal-for-the-first-time-ever

And here's the paper published in Science.

Quote
Abstract
Producing metallic hydrogen has been a great challenge to condensed matter physics. Metallic hydrogen may be a room temperature superconductor and metastable when the pressure is released and could have an important impact on energy and rocketry. We have studied solid molecular hydrogen under pressure at low temperatures. At a pressure of 495 GPa hydrogen becomes metallic with reflectivity as high as 0.91. We fit the reflectance using a Drude free electron model to determine the plasma frequency of 32.5 2.1 eV at T = 5.5 K, with a corresponding electron carrier density of 7.7 1.1 1023 particles/cm3, consistent with theoretical estimates of the atomic density. The properties are those of an atomic metal. We have produced the Wigner-Huntington dissociative transition to atomic metallic hydrogen in the laboratory.

http://science.sciencemag.org/content/early/2017/01/25/science.aal1579?

More in this article.

Metallic hydrogen created in diamond vise

Quote
In 1935 a pair of physicists predicted that if the pressure of hydrogen were raised to about 25 times that of atmospheric pressure, it would turn into a solid metal. Experimentalists ever since have tried and failed to spot this transition, even after raising the pressure of hydrogen to millions of times atmospheric pressure. Now, the transition to solid metallic hydrogen may have been reached. Physicists in the United States say that by crushing a tiny amount of hydrogen between the tips of two flat-tipped diamonds at cryogenic temperatures they've raised the pressure to nearly 5 million times atmospheric pressure, causing the hydrogen to reflect light like a metal. They still don't have evidence the pressurized hydrogen is a solid. But even the claim that it is metallic is highly controversial. Other high-pressure physicists question some of the procedures used in the new study, and say they need more proof before they'll concede that the 80-year quest is over.

http://science.sciencemag.org/content/355/6323/332

This is astonishing. If it is found to be metastable and can be made in large enough quantities it can change a number of things. Room temperature superconductor. VTOL SSTO etc.

To put 1700secs in perspective the target for NERVA NTR was 825secs with a T/W ratio of 5.35:1.
combining this with Argon (cheapest noble gas) would knock the Isp down a bit, reduce the amount of MH needed and still leave a substantial Isp to give a vehicle with a reasonable PMF.

But in terms of applications everything hinges on it remaining like that for a significant time after the pressure is removed.
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline Star One

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Metallic Hydrogen is real!
« Reply #51 on: 01/27/2017 06:54 AM »
It was also hardly easy to manufacture considering the amount of preparation they had to make with the synthetic diamond vice alone. That pressure is ridiculous as well and how much energy did that use to create. Going to be as much about how you manufacture it as to if it's metastable.
« Last Edit: 01/27/2017 06:56 AM by Star One »

Offline Welsh Dragon

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Re: Metallic Hydrogen is real!
« Reply #52 on: 01/27/2017 07:32 AM »
And because the research was published in Science, Nature tries to spoil the party: http://www.nature.com/news/physicists-doubt-bold-report-of-metallic-hydrogen-1.21379
Don't be childish. Extraordinary claims require extraordinary evidence. If other scientists don't try to pick your research apart, it's not interesting. This is how science works. It's not "spoiling the party".

Offline Nilof

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Re: Metallic Hydrogen is real!
« Reply #53 on: 01/27/2017 08:44 AM »
The paper that this is all based on is available here: https://arxiv.org/abs/1610.01634
For a variable Isp spacecraft running at constant power and constant acceleration, the mass ratio is linear in delta-v.   Δv = ve0(MR-1). Or equivalently: Δv = vef PMF. Also, this is energy-optimal for a fixed delta-v and mass ratio.

Offline Star One

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Metallic Hydrogen is real!
« Reply #54 on: 01/27/2017 12:38 PM »
The paper that this is all based on is available here: https://arxiv.org/abs/1610.01634

That is not the peer reviewed paper you can tell from the date.
« Last Edit: 01/27/2017 12:38 PM by Star One »

Offline Nilof

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Re: Metallic Hydrogen is real!
« Reply #55 on: 01/27/2017 06:04 PM »
The paper that this is all based on is available here: https://arxiv.org/abs/1610.01634

That is not the peer reviewed paper you can tell from the date.

It is however the preprint for the same paper. Preprints pop up on the arxiv a few months before the journal article and are typically used to claim priority for the discovery. The article that ends up in the journal will usually have the same content with some minor change in editing, and mainly serves the purpose of giving the author legitimacy/career points. Specificially it's there so that researchers that haven't followed the field closely can gauge the author.

I've been through that process myself in my own publications. In the most active fields, other researchers in the same field pretty much only read the arxiv preprints because they'll be several months behind everyone else if they wait for the journal version, which will often also be behind an annoying paywall that makes citation trails harder to follow.

The published article can be found here, but as expected it is behind a paywall: http://science.sciencemag.org/content/early/2017/01/25/science.aal1579.full
« Last Edit: 01/27/2017 06:15 PM by Nilof »
For a variable Isp spacecraft running at constant power and constant acceleration, the mass ratio is linear in delta-v.   Δv = ve0(MR-1). Or equivalently: Δv = vef PMF. Also, this is energy-optimal for a fixed delta-v and mass ratio.

Offline Welsh Dragon

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Re: Metallic Hydrogen is real!
« Reply #56 on: 01/28/2017 07:09 AM »
Note that while I'm sure that's true in physics, it varies by field. It's certainly not true in my field of biology. But I agree, that preprint is the next best thing if you don't have access to the actual paper.

Offline Star One

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Re: Metallic Hydrogen is real!
« Reply #57 on: 01/28/2017 08:00 AM »
It's shame so many Scientific papers end up behind paywalls and expensive journals.

Offline Welsh Dragon

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Re: Metallic Hydrogen is real!
« Reply #58 on: 01/28/2017 08:10 AM »
Oh don't even get me started on that! The publishing model is so broken. Never mind the fact that I have to pay thousands of pounds to have my research published open access (as is correctly required by most funding bodies now). It won't last, something's got to give. But this is very off topic here now, I do apologise. Rant over!

Offline as58

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Re: Metallic Hydrogen is real!
« Reply #59 on: 01/28/2017 08:13 AM »
There are some curious patterns about how arxiv usage varies by field. Close to 100% of new astronomy/astrophysics papers are on arxiv, but for some reason it's not widely used by planetary scientists (though it seems to be improving). In physics, mathematics, and computer science some subfields are also close to 100%, while in others it's less common. It seems to me that people in more applied subfields are less likely to put their papers on arxiv.

I read very few new articles in journals because in my field almost everything goes to arxiv, usually months before publication. The exceptions are the biggest news that have embargoes and get announced in press conferences

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