"Richard Smith" wrote in message news:ly7cxhfooo.fsf@void.com...

Norman - no-one previously knew there was a more than 3-fold
difference in the diffusivity ("movement rate") of hydrogen in "plate
steels" - thicker C-Mn steels used for general construction,
pipelines, ships, etc.
I found that out experimentally early on.
That was a surprise. It had my thoughts going on a path which lead to
"the sixth-jumping solution".
In all fairness - those initiating and putting together the project
had that intuition that movement could surely be the only aspect
concealing the explanation seeing as so much is / was known about
other things. The steel samples they had assembled for me was an
embodiment of that intuition of theirs.
But in all fairness to me - I found the test(s) which revealed the
hydrogen-movement behaviour, when everyone else thought it
all-but-impossible.
My experiments had about the same qualities as my computational model
/ solution, I suggest...

My "Wedge Weld Hydrogen Penetration" test - that only works because
there are things going on we do not understand. But the pattern of
results is so exact - movement-distance is strictly proportional to
square-root of time always as ever seen. So there was confidence to
use this "unexpected bounty".
But the thing is, I did a "scattergun" approach early on, with
"dead-certs" not working at all and "almost no hope'ers" astonishing
with being workhorses - the WWHP test being one.

You are clearly a scientist - there were about four previous
scientific papers on hydrogen mmovement in welds - none with any
analysis of what physical phenomena are giving the results.
You will be knowing - that is double-unusual.
* tiny number of previous investigations reported (and that being more
because cooperation in welding science never ceased during the Cold
War)(you'd be expecting thousands minimum given the economic,
commercial and military relevance).
* a scientific paper published with no mechanistic model trying to
explain the results is rare

So that investigation could have been subtitled "To boldly go where
no-one considered it a particularly good idea to go before".

-----------------------

Diffusion of atoms is extremely important, thoroughly studied and fairly
easy to measure over distance and time in semiconductor fabrication. I was
on a team that designed and built the necessary instruments for automated
production testing. The electrical properties of Silicon are very sensitive
to the concentration of trace amounts of other atoms.
https://www.eeeguide.com/diffusion-process-in-ic-fabrication/

BTW "Fick" is the basic 4-letter-word in German.

Norman Yarvin <norman.yarvin@gmail.com> writes:

> On Friday, January 20, 2023 at 3:09:54 AM UTC-5, Richard Smith wrote:
>> Norman - the reality at the time, in the early 1990's, was that these
>> German and Japanese Thermo-Mechanically Controlled-Processed plate
>> High-Strength Low-Alloy steels were so superior, leaving "us" having
>> to buy these steels and put them through our pipe-mills while plate
>> capacity here stood idle.
>
> Has that improved? (Or has it gotten worse, with no longer even a
> British attempt to compete?)

My PhD research should have been subtitled
"To boldly go where no-one thought it a particularly good idea to go"
(parody on "Star Trek" upbeat theme)
and when I completed it, after the scientifically posed "Conclusions"
the common-language ultra-brief summary would have been
"You're screwed".

The properties of the TMCP steels seems only attainable using the TMCP
production route. The TMCP steels have a very "clean" microstructure
of very fine ferrite grains. Nothing else. Tiny precipitates which
with a scanning electron microscope (SEM) you can resolve are just
that - some very fine solid precipitates. Presumably reaction
products of the "fine" additions of the likes of Titanium to an
already very clean pure highly deoxidised melt. (I had not the budget
and it was of no importance to my work to use electron spectographic
methods to analyse what they were - what SEM I got was a "gift"
anyway).

Other ways to get the same properties would cost a lot lot lot in
alloying elements and would have none of the weldability and
sour-crude-oil resistance. Total non-starter.

I have never seen one of these, and no photos are released, but I do
know a few who have seen the rolling mill stand(s) in a
Thermo-Mechanically Controlled-Processed plate steel plant and they
are apparently jaw-droppingly awesome. They "work" the steel with
heavy reductions at blood-red heat (not light reductions at
yellow-heat). There was not possibility to make that investment here.

So the answer is "No".

> ...
> Diffusion of atoms is extremely important, thoroughly studied and
> fairly easy to measure over distance and time in semiconductor
> fabrication. I was on a team that designed and built the necessary
> instruments for automated production testing. The electrical
> properties of Silicon are very sensitive to the concentration of trace
> amounts of other atoms.
> https://www.eeeguide.com/diffusion-process-in-ic-fabrication/
> ...

Yes.
But with hydrogen in steel the hydrogen is moving millimetres in minutes.
What you'd do for every other element - take a slice and measure the
concentration-at-position in the hours days and weeks following - very
specifically cannot work for hydrogen in steel.
Restating:
if you try to slice a sample with intent to measure the hydrogen in
it, the hydrogen would be long-gone by the time you had your slice.

There is then an additional problem. Suppose you had your slice of
steel with the hydrogen it had previously still all there in the
conentration profile it had...
How are you going to measure that hydrogen concentration in-situ???
Element #1 - you can name a spectroscopic method which would tell you
what concentration of hydrogen is there?
(hypothetically - "neutron spectroscopy" - but there is no such
instrument with fine beam to spot-probe and plot concentration
*profile* - a hole in the wall of a running nuclear reactor gives a
"uniform illumination" (?))

That is why no-one had managed to touch this topic before - despite
all the steel welded in the world, no-one had information where the
weld hydrogen went and in what time-scale. Yes, cracks in the weld
metal and heat affected zone said "'ydrogen woz 'ere" but that's about
it...

That's why I work as a welder - I frightened everyone doing what I did
- and to be honest was very broken and damaged myself after getting
through that.
Then furthermore, what I discovered didn't fit with text-book writings
- and no-one questions what is written even if "God" seems to be
saying otherwise.

Etc.

Best wishes,

Norman Yarvin <norman.yarvin@gmail.com> writes:

> ...

> To me it's just "diffusion": with that sort of basic process -- particles
> wandering around randomly -- it's hard for there to be any other
> governing law.

> ...

No way!!!

"Random" is the problem - it is hardly likely to be so.

For two element types to co-exist in one space with no interaction is
hardly probable. Fick recognises that. He gave us a baseline: "What
would happen if there were no interaction". Everyone then has to be
realistic - that is a "baseline" reference case but is almost never
going to happen.

My computing solution is a "caveperson with a wooden club" method and
should be recognised as such.

You are obviously very bright.

Then there are other things going on we absolutely do not know about.
"Asymmetric diffusion", where the rate the solute enters the solid
solvent does not match the rate the solute leaves the solid solvent,
was previously known and observed.
Broadly the "in" rate is Fickian, but the "out" rate is slower and
"something else" for hydrogen in steel.

Even what we do know - that for treatments like cold-working steel the
product (multiplication) of solubility and diffusivity stays the same
with increasing cold-work (cold work increases - S increases; D
decreases) (the "permeability" - seen abundantly elsewhere in-support)
- which means that solubility and diffusivity must be dependent
variables on the same one underlying independent physical state - got
massive explosive vitriolic response when I counselled that at the
time about 20 years ago to someone dealing with hydrogen. Academics
who were absolutely livid at the suggestion which is to be seen right
there "exact" in experimental data.

Back to movement and "something else" happening...

I found that this is happening in steel welds.
That is why I needed my computational solution.

"Fickian" assumptions are used as the best guess in explaining clauses
in Standards for welding and hydrogen - but I showed for certain the
reality is something else.

I could visualise experiments to try to "break into that" / "get a
window into what is going on" - but that would have needed a new
project, and I'd gone through two Universities and three supervisors
just getting this project done...

Best wishes,

"Richard Smith" wrote in message news:lycz763kcp.fsf@void.com...

> ...
> Diffusion of atoms is extremely important, thoroughly studied and
> fairly easy to measure over distance and time in semiconductor
> fabrication. I was on a team that designed and built the necessary
> instruments for automated production testing. The electrical
> properties of Silicon are very sensitive to the concentration of trace
> amounts of other atoms.
> https://www.eeeguide.com/diffusion-process-in-ic-fabrication/
> ...

Yes.
But with hydrogen in steel the hydrogen is moving millimetres in minutes.
What you'd do for every other element - take a slice and measure the
concentration-at-position in the hours days and weeks following - very
specifically cannot work for hydrogen in steel.
Restating:
if you try to slice a sample with intent to measure the hydrogen in
it, the hydrogen would be long-gone by the time you had your slice.

There is then an additional problem. Suppose you had your slice of
steel with the hydrogen it had previously still all there in the
conentration profile it had...
How are you going to measure that hydrogen concentration in-situ???
Element #1 - you can name a spectroscopic method which would tell you
what concentration of hydrogen is there?
-------------------
Raman lidar.
-------------------
(hypothetically - "neutron spectroscopy" - but there is no such
instrument with fine beam to spot-probe and plot concentration
*profile* - a hole in the wall of a running nuclear reactor gives a
"uniform illumination" (?))

That is why no-one had managed to touch this topic before - despite
all the steel welded in the world, no-one had information where the
weld hydrogen went and in what time-scale. Yes, cracks in the weld
metal and heat affected zone said "'ydrogen woz 'ere" but that's about
it...

That's why I work as a welder - I frightened everyone doing what I did
- and to be honest was very broken and damaged myself after getting
through that.
Then furthermore, what I discovered didn't fit with text-book writings
- and no-one questions what is written even if "God" seems to be
saying otherwise.

Etc.

Best wishes,

------------------------------

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5090567/
"Only at higher temperatures are the values from different works [diffusion
rate measurements] close to each other; at room temperature differences in
the order of three magnitudes are observed. This is a direct result of the
interaction of hydrogen dissolved interstitially in the crystal lattice and
lattice defects in the iron, such as vacancies, foreign atoms, dislocations,
grain boundaries, voids and other defects. Most of these defect sites tend
to react exothermally with interstitial hydrogen, as opposed to the
endothermic dissolution of hydrogen in the lattice, and constitute traps for
hydrogen uptake, respectively sources for hydrogen release. The effective
diffusion coefficient of hydrogen in the presence of defect sites is always
smaller than that of ideally dissolved hydrogen in the defect-free perfect
crystalline lattice."

Is the rate of diffusion through a thin sheet relatable to the rate of
diffusion the same distance into a solid?

For real-time measurement:
https://unisense.com/products/h2-microsensor/

For integrated measurement, hydrogen can reduce silver and copper compounds
to the metal, and increase the sensitivity of photo film.

"Jim Wilkins" wrote in message news:tqkid4$3aek4$1@dont-email.me...

'The effective
diffusion coefficient of hydrogen in the presence of defect sites is always
smaller than that of ideally dissolved hydrogen in the defect-free perfect
crystalline lattice."

----------------------

Inversely, the rate of diffusion might be a measure of the quality of the
steel.

"Jim Wilkins" <muratlanne@gmail.com> writes:

> "Richard Smith" wrote in message news:lycz763kcp.fsf@void.com...
>
>> ...

> ...

> -------------------
> Raman lidar.
> -------------------

> ...
>
> https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5090567/
> "Only at higher temperatures are the values from different works
> [diffusion rate measurements] close to each other; at room temperature
> differences in the order of three magnitudes are observed. This is a
> direct result of the interaction of hydrogen dissolved interstitially
> in the crystal lattice and lattice defects in the iron, such as
> vacancies, foreign atoms, dislocations, grain boundaries, voids and
> other defects. Most of these defect sites tend to react exothermally
> with interstitial hydrogen, as opposed to the endothermic dissolution
> of hydrogen in the lattice, and constitute traps for hydrogen uptake,
> respectively sources for hydrogen release. The effective diffusion
> coefficient of hydrogen in the presence of defect sites is always
> smaller than that of ideally dissolved hydrogen in the defect-free
> perfect crystalline lattice."
>
> Is the rate of diffusion through a thin sheet relatable to the rate of
> diffusion the same distance into a solid?
>
> For real-time measurement:
> https://unisense.com/products/h2-microsensor/
>
> For integrated measurement, hydrogen can reduce silver and copper
> compounds to the metal, and increase the sensitivity of photo film.

Correct. Exactly so. "Trapping". By 300degC and upwards all steels
are showing the same diffusivity to hydrogen accordign to all
experimental data - they all interlock to say that.

Thanks
"Raman Lidar"

Too complex to say that, really, I believe

"Richard Smith" wrote in message news:lyh6wh7jwa.fsf@void.com...

Thanks
"Raman Lidar"

--------------------

If the H2 concentration is high enough there are commercial sensors.
https://www.amazon.com/HYDROGEN-FORENSICS-Professional-Explosion-Vibration/dp/B07CRLQZFW

I assume you'd need a narrow probe to sense in a drilled hole, a data output
to record the changing rate, local support and an affordable cost, so I
didn't look further. It can be done. The Mass Air Flow sensor in a car was
adapted from the gas chromatograph and might be cobbled into a DIY hydrogen
detector, and possibly a Coleman lantern mantle would provide the
heat-producing catalyst. Google didn't help there, and I'm too far away and
busy with my own projects to provide hands-on interactive lab tech support.
https://e2e.ti.com/support/sensors-group/sensors/f/sensors-forum/1061992/how-can-i-design-a-wheatstone-bridge-signal-processing-of-gas-sensor

I worked at a company that had a semiconductor fab line and gas sensors to
detect leaks. There was an oxygen monitor next to the liquid nitrogen cooled
wafer probe (IC test) station because we breathe to reduce CO2 acidity in
the blood and aren't aware of lack of oxygen.

"Jim Wilkins" wrote in message news:tqm0vg$3kkvv$1@dont-email.me...
If the H2 concentration is high enough there are commercial sensors.

---------------------------
Carbon monoxide detectors also sense hydrogen, this claims they display 10%
of the actual concentration.
https://chemistry.stackexchange.com/questions/81308/can-lead-acid-batteries-release-co-or-can-a-co-sensor-detect-gasses-other-than

Here's a small, cheap hydrogen sensor for a do-it-yourself project:

https://www.l-com.com/h2-sensor-modulemq8-50-10000ppmanalog-ttl-output-sraq-g013?gclid=Cj0KCQiA_bieBhDSARIsADU4zLfPelOr3Iycu3HISzQIXUi7KUS-WRNvllq4aRWdtUS7JSNmHJ_agK8aAl8BEALw_wcB

https://www.l-com.com/Images/Downloadables/Manuals/M_SRAQ-G013.pdf

https://www.winsen-sensor.com/sensors/h2-sensor/mq8.html

On Sunday, January 22, 2023 at 6:24:25 AM UTC-5, Richard Smith wrote:

>Norman Yarvin writes:
>
>> To me it's just "diffusion": with that sort of basic process -- particles
>> wandering around randomly -- it's hard for there to be any other
>> governing law.
>
>> ...
>
>No way!!!
>
>"Random" is the problem - it is hardly likely to be so.

Oh, it's definitely a random process: thermal energy causing all the
atoms to vibrate and the looser ones (like hydrogen) to wander around.
But there are a lot of different random processes.

Your objection would have been better addressed to the words
"wandering around" -- because thinking it over again, I see you have a
point. Suppose that on average the hydrogen atoms spent almost no
time wandering around and almost all of their time stuck in some trap
(some local energy well). Then, at equilibrium, a part of the
material with twice as many traps would have almost twice as many
hydrogen atoms, since at equilibrium the concentration of hydrogen
atoms *that are wandering around* is equal everywhere. (That last is
the part of my argument that survives.)

Now, the hydrogen atoms have to spend some of their time wandering
around, or there wouldn't be diffusion at all. But it might be close
enough to zero that the difference can be neglected. In any case, if
a fraction X of them are trapped and the rest are wandering, then the
concentration ratio is 2:1 for the trapped ones and 1:1 for the
wandering ones, so an overall ratio of (1+X):1.

Of course that's just considering equilibrium; in general the thing to
do is to apply the diffusion equation only to the fraction of the
population that is actively diffusing, and couple that to some other
equation that models the kinetics of getting trapped and released.

But even that is just a thought experiment, since there most probably
aren't just two states ("trapped" and "untrapped"), but rather a whole
spectrum of different energy levels, with the lower ones being trapped
states and the higher ones being wandering-around states. That's the
realm of statistical mechanics, about which it has been said:

"Ludwig Boltzmann, who spent much of his life studying
statistical mechanics, died in 1906, by his own hand. Paul
Ehrenfest, carrying on the work, died similarly in 1933. Now
it is our turn to study statistical mechanics. Perhaps it will
be wise to approach the subject cautiously."

(Opening lines of "States of Matter", by D.L. Goodstein).

>Then there are other things going on we absolutely do not know about.
>"Asymmetric diffusion", where the rate the solute enters the solid
>solvent does not match the rate the solute leaves the solid solvent,
>was previously known and observed.

You seemed to know the reason when you were writing your thesis: it's
the result of a difference in energy levels between the two sides,
with one side having a greater chemical affinity to the substance that
is diffusing and thus readily sucking it out from the other side.
(And with hydrogen in particular, the hydrogen molecule having to
dissociate into hydrogen atoms before it can penetrate the steel,
with that dissociation requiring a lot of energy.)

>Even what we do know - that for treatments like cold-working steel the
>product (multiplication) of solubility and diffusivity stays the same
>with increasing cold-work (cold work increases - S increases; D
>decreases) (the "permeability" - seen abundantly elsewhere in-support)
>- which means that solubility and diffusivity must be dependent
>variables on the same one underlying independent physical state - got
>massive explosive vitriolic response when I counselled that at the
>time about 20 years ago to someone dealing with hydrogen. Academics
>who were absolutely livid at the suggestion which is to be seen right
>there "exact" in experimental data.

Not all academics are like that. Feynman wrote that when he was
investigating the Space Shuttle disaster, he got along fine with the
people who worked on the solid rocket boosters: he knew stuff from
theory and they knew it from practice, but all were on the same page.

That said, your style is a sort that raises the hackles of theorists:
you're making theoretical statements (trespassing on their turf) but
doing so using crude arguments: it makes them feel like they're under
barbarian invasion. It's a theorist's job to explain experiments and
to look past any crude justifications an experimenter offers, but not
everybody is good at their job.

--
Norman Yarvin
yarvin@yarchive.net

On Sunday, January 22, 2023 at 5:43:55 AM UTC-5, Richard Smith wrote:
> Norman Yarvin writes:
>
> > Has that improved? (Or has it gotten worse, with no longer even a
> > British attempt to compete?)
> My PhD research should have been subtitled
> "To boldly go where no-one thought it a particularly good idea to go"
> (parody on "Star Trek" upbeat theme)
> and when I completed it, after the scientifically posed "Conclusions"
> the common-language ultra-brief summary would have been
> "You're screwed".

That much I gathered. But there are a lot of things that can happen
in the world: sometimes failing British companies have been bought
by their German competitors and revamped.

"Norman Yarvin" wrote in message
news:2c734b42-916b-4807-8a6c-109de60eab43n@googlegroups.com...

....
But even that is just a thought experiment, since there most probably
aren't just two states ("trapped" and "untrapped"), but rather a whole
spectrum of different energy levels, with the lower ones being trapped
states and the higher ones being wandering-around states. That's the
realm of statistical mechanics, about which it has been said:

"Ludwig Boltzmann, who spent much of his life studying
statistical mechanics, died in 1906, by his own hand. Paul
Ehrenfest, carrying on the work, died similarly in 1933. Now
it is our turn to study statistical mechanics. Perhaps it will
be wise to approach the subject cautiously."

(Opening lines of "States of Matter", by D.L. Goodstein).
....
Norman Yarvin
yarvin@yarchive.net

---------------------

Read at your own risk:
https://en.wikipedia.org/wiki/Activation_energy
https://en.wikipedia.org/wiki/Maxwell%E2%80%93Boltzmann_distribution

Einstein accepted that Quantum theory explained observed results but he
didn't believe it was the real answer. He died of heart failure.
https://www.amnh.org/exhibitions/einstein/legacy/quantum-theory

> Raman Lidar
> {other detectors}

Ahhh...
The problem is that these are detecting hydrogen after it has already
left the sample.
The fundamental scientific issue is that how hydrogen leaves the
"solid solvent" iron/steel is complex in ways we don't know.

Scientists have run round and round in circles with the Devanathan and
Stachurski (?) electrochemical permeation cell because it introduces
two surfaces not part of the what happens within a solid object - the
surface though which the hydrogen is input and the surface through
which hydrogen leaves (the electrochemical permeation cell has the
sample as a disc / wafer). It has been realised that what happens at
those surfaces tends to dominate the results and little of what you
measure in this apparently "perfect" method is what's happening
*within* the sample.

That is why I enraged some "scientists" - at the outset I "threw-out"
any theory or method which did not have a ready demonstration that it
really works like that.

Against much fury, I started with "hydrogen does move in steels".
Then had only hydrogen bubble formation in glycerol as my detection
method.
Something wise scientists will tell you - it's something like "You
cannot browbeat God".
That is at the root of finding your way into a subject, seeing what is
there and conveying what you have seen ("creating new knowledge").

Your "Raman Lidar" would work for a thin sample extracted from eg. a
weld, at liquid nitrogen temperature (hydrogen is "condensed" on
"traps" and is immobile) and that sample suddenly brought back to
room-temperature.
You could have the laser beam scanning the sample - likely a
raster-pattern, plotting {rate of hydrogen evolution (inferred by
hydrogen concentration in the gas surrounding} vs {position (x-y
coordinates)}.
There is no guessing how well this would work (?).

Norman Yarvin wrote:

> ...
> you're making theoretical statements (trespassing on their turf) but
> doing so using crude arguments: it makes them feel like they're under
> barbarian invasion.
> ...

Roaring with laughter!!!

Yes, I had that self-perception.

You are "running with the baton" now (analogy to a relay race), and I
work as a welder mainly on marine (boats, etc) and marine civils.

That said; in welding I went for an interview at an esteemed offshore
engineering Company in the oil&gas sector and the panel of four
interviewers behind the desk had to hold onto that desk to avoid
falling off their chairs at one response. They had picked a
fascination I did not share with the sequence of small
rough-as-... steel fabrications companies I had worked for and a
somewhat disengaged answer had then wiped-out. My response conjured
up a world where more than half the people who tendered their
resignation scripted it in the "four knuckles format".

Happy to read your comments.
Best wishes

Norman Yarvin <norman.yarvin@gmail.com> writes:

> On Sunday, January 22, 2023 at 5:43:55 AM UTC-5, Richard Smith wrote:
>> Norman Yarvin writes:
>>
>> > Has that improved? (Or has it gotten worse, with no longer even a
>> > British attempt to compete?)
>> My PhD research should have been subtitled
>> "To boldly go where no-one thought it a particularly good idea to go"
>> (parody on "Star Trek" upbeat theme)
>> and when I completed it, after the scientifically posed "Conclusions"
>> the common-language ultra-brief summary would have been
>> "You're screwed".
>
> That much I gathered. But there are a lot of things that can happen
> in the world: sometimes failing British companies have been bought
> by their German competitors and revamped.

Too far gone; nothing worth having.
Sad.
The person who mentored me on my metal and fatigue investigation and
knowledge told me the path to Thermo-Mechanically Controlled-Processed
steels started when to get seriously far North in the North Sea the
British engineers needed steels with exceptional properties and could
see how that could be obtained. Apparently the British steel
companies "took a sensible view about this fringe product" and the
Japanese made these super-refined (compared to anything before) plate
C-Mn steels. Then the development path and there they are, the
Japanese and Germans, the established incumbents able to meet all
market demand.
Told me that - note that distinction.

"Richard Smith" wrote in message news:ly1qnkphod.fsf@void.com...
....
There is no guessing how well this would work (?).

---------------------

It would have to be calibrated against another method.

https://www.sciencedirect.com/science/article/abs/pii/0001616063902141
"An increase of the electrical resistance of the wires due to the cracks and
an increase due to coldworking, could be measured as two distinctly
different effects. No change in the resistance due to interstitial solution
of hydrogen could be detected."

"Jim Wilkins" wrote in message news:tqoiu7$4qou$1@dont-email.me...

"Richard Smith" wrote in message news:ly1qnkphod.fsf@void.com...
....
There is no guessing how well this would work (?).

---------------------

It would have to be calibrated against another method.

No change in the resistance due to interstitial solution
of hydrogen could be detected."

-----------------------

I'm still looking for cheap DIY methods. It appears that heavily anodized
aluminum might be a good low permeability material for a chamber in which to
pressurize steel samples with hydrogen and test sensors, and quickly
evacuate the chamber, electrically heat the sample and measure the amount of
outgassed hydrogen.

A vacuum chamber can be a piece of tubing with thick plate ends clamped by
tie rods. The seals can be O rings in grooves turned in the tube ends.

https://www.amazon.com/Super-Lube-91003-Silicone-High-Dielectric/dp/B002KH0YDY/ref=sr_1_4?keywords=vacuum+grease&qid=1674568160&sr=8-4

https://gigabecquerel.wordpress.com/2019/06/02/quick-n-dirty-vacuum-feedthrough/

On Monday, January 23, 2023 at 6:24:34 PM UTC-5, Jim Wilkins wrote:

> https://en.wikipedia.org/wiki/Maxwell%E2%80%93Boltzmann_distribution

For hydrogen diffusion in steel, you have to go a bit farther on, to
the Fermi-Dirac distribution:

https://en.wikipedia.org/wiki/Fermi%E2%80%93Dirac_statistics

(Neither Fermi nor Dirac met such sad ends.)

> Einstein accepted that Quantum theory explained observed results but he
> didn't believe it was the real answer.

His line "God doesn't play dice with the universe" deserved the
response it got (roughly "don't tell God what to do".) But he wasn't
wrong that quantum theory needed work. The modern "decoherence"
theory of quantum measurement might have satisfied him:

https://infoproc.blogspot.com/2022/12/decoherence-and-quantum-measurement.html

On Tuesday, January 24, 2023 at 1:31:33 AM UTC-5, Richard Smith wrote:
>Your "Raman Lidar" would work for a thin sample extracted from eg. a
>weld, at liquid nitrogen temperature (hydrogen is "condensed" on
>"traps" and is immobile) and that sample suddenly brought back to
>room-temperature.
>You could have the laser beam scanning the sample - likely a
>raster-pattern, plotting {rate of hydrogen evolution (inferred by
>hydrogen concentration in the gas surrounding} vs {position (x-y
>coordinates)}.
>There is no guessing how well this would work (?).

I bet it could be done by freezing the welded sample down to liquid
nitrogen temperatures, then hitting it with a high-power pulsed laser
that instantly vaporized a small part of the surface, feeding the
gases that came out into a mass spectrometer to detect the hydrogen.
(Yes, optical detection is another possibility, but it might struggle with
the low concentration, whereas mass spectrometers are good at
detecting exceedingly small concentrations.) The process could then
be repeated until the sample was entirely consumed and you had
hydrogen numbers for each little piece of it. Or if that would take
too much time you could take a representative slice through it.

Of course that'd be quite a formidable apparatus, requiring much money
and years of work by several people.

---
Norman Yarvin
yarvin@yarchive.net

"Norman Yarvin" wrote in message
news:78e4e745-cb33-4d18-b776-a60b1c956011n@googlegroups.com...

I bet it could be done by freezing the welded sample down to liquid
nitrogen temperatures, then hitting it with a high-power pulsed laser
that instantly vaporized a small part of the surface, feeding the
gases that came out into a mass spectrometer to detect the hydrogen.

Norman Yarvin
yarvin@yarchive.net

-----------------------

It appears that the reason hydrogen in steel hasn't been studied is lack of
instruments, not lack of interest.
XRF is another analytical technique that doesn't work for it, or other light
elements.

https://nmi3.eu/neutron-research/techniques-for-/imaging.html

The Fusor is a tabletop fusion reactor that emits neutrons.
https://en.wikipedia.org/wiki/Fusor
"Most recently, the fusor has gained popularity among amateurs, who choose
them as home projects due to their relatively low space, money, and power
requirements."

Richard Smith wrote:
....
> The "sixth-jumping" technique came to me having read Adolf Fick's
> original 1855 (?) scientific paper.
....

See [*] for a related technique (known in the 1930s and possibly earlier).
[*] <https://en.wikipedia.org/wiki/Relaxation_(iterative_method)>

In the 2D case, "To approximate the solution of the Poisson equation
.... numerically on a two-dimensional grid with grid spacing h, the
relaxation method assigns the given values of function phi to the grid
points near the boundary and arbitrary values to the interior grid
points, and then repeatedly performs the assignment phi := phi* on the
interior points, where phi* is..." 1/4 of sum of neighbor cells, less
an f(x,y) term. Your case with two different D regions would mean
using two different phi* equations, but I don't see that as a problem.
Where the relaxation method (at least as stated in [*]) doesn't quite
fit is that it starts with given boundary conditions and computes
until interior point values reach equilibrium, while your process is
given some initial interior values and evolves the state from there,
not necessarily reaching a nonzero equilibrium.

> I saw that if you have "an automatic computer" ("a computer") you
> don't need to formulate differential equations.

Need to formulate DE's to have a model to be solved, but don't need
analytical solutions if the computer can quickly approach a solution
that's accurate enough and provides enough insight. (An example of
slowness and limited insight: The writer of following ca 1950 thesis
says it only took 7 hours to compute a relaxation solution for a heat
transfer problem on 50 points. It probably would take a couple of
milliseconds nowadays and there would be an informative graphic as well.)
<https://scholarsmine.mst.edu/cgi/viewcontent.cgi?article=5895&context=masters_theses>

> A person of Middle-Eastern origin showed me the computational method
> for solving mathematical integration ("calculus") approximately but
> achievably. But having seen that, my "sixth-jumping model" came to
> me. My sixth-jumping model used as a general solution does have
> "convergence" with increasing discretisation, by the way, stating the
> obvious.
....

The mid-point method of numerical integration is not bad -- its error
is O(h^3), for intervals of width h -- but Simpson's rule, for about
the same cost per step, has far smaller error, O(h^5). Eg, where the
midpoint rule might need hundreds or perhaps thousands of divisions to
compute a 9-decimals value of erf(x), Simpson's needs fewer than 40.
<https://en.wikipedia.org/wiki/Riemann_sum#Midpoint_rule>
<https://en.wikipedia.org/wiki/Simpson's_rule>