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#76 2016-06-15 04:28:22

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 4,993
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Re: Power generation on Mars

Yesterday I saw a TV show called "How It's Made". They go through the manufacturing process. A lot of detail is skipped, but it's interesting. This episode covered CCD image sensors. That made me think of photovoltaic cells (solar cells) for power generation on Mars. I've read about how they're made, but this video shows it.

The full episode is available here: How It's Made - CCD Semiconductors - Airline Meals - Paper Cups - Trumpets
It's 20:47 in length (20 minutes, 47 seconds) and includes those other things. But includes the voice of the Canadian narrator for shows that air here in Canada.

Just the section about CCD is available here: How It's Made CCD Semiconductors
It's 5 minutes long. A different narrator, I think American, but exactly the same script and same video. It's actually at least 8 years old, but shows how electronics are made.

When the episode started I had hopes we would see how to make electronics, or at least photovoltaics, in a practical way. Perhaps not. Equipment and chemicals still look like it'll be a long time before we can do this on Mars.

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#77 2016-06-17 19:32:17

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 4,993
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#78 2016-06-17 19:40:18

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 10,527

Re: Power generation on Mars

The processes that are used in many a building technique is vapor deposition of the materials onto the substrate which then is dried then sprayed with a masking agent to which a photographic image is is created then etched away to then vapor deposit the next layer and so forth until the junctions are made between the electrical contacts.....
Fabrication of efficient planar perovskite solar cells using a one-step chemical vapor deposition method

https://dash.harvard.edu/handle/1/12274544

http://ntrs.nasa.gov/search.jsp?R=20100002254

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#79 2016-07-05 04:03:13

elderflower
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Registered: 2016-06-19
Posts: 521

Re: Power generation on Mars

C M Edwards wrote:

I should point out that few to none of the reactors previously launched into space (the numbers are skewed by varying degrees of secrecy) have been capable of more than 10kW, and none exceeding 2kW are known to have lasted more than 6 months.

Check out a rough list of known reactors in orbit here:

http://www.globenet.free-online.co.uk/ianus/npsm1.htm

Solar arrays can be built with these outputs, and with better reliability.

CME

I believe these were isotope generators, rather than critical nuclear reactors. The output of the latter would be measured in megawatts.

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#80 2016-07-09 11:55:43

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 10,527

Re: Power generation on Mars

Isotope generators are simular to the cold fusion topics of the E-Cat and LNRL research that has been going on for some time now. The issue for mars is colllecting and processing the isotope to the stage to make these devices work....

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#81 2016-07-10 13:24:41

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 2,692
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Re: Power generation on Mars

I read an article in the latest issue of AAAS's journal "Science" about high-efficiency perovskite PV cells.  Up to now,  the nominal 20% efficiency (that everybody ballyhoos) goes with dimensions on the order of a mm or two (something kept quiet).  Bigger simply would not work efficiently,  for reasons outside what I know and understand.  This latest article showed a 20% efficiency result for a perovskite cell of 1 cm dimensions,  formed with a vapor deposition process.  It still doesn't work any larger than that,  which is what we really need for a proper piece of equipment:  2-5 cm dimension. 

What that goes to prove is what I have long contended:  there is a vast gulf between what can be demonstrated in a science lab,  and what is actually needed for a piece of equipment that really works under field conditions.  Science lab results papers are overoptimistic,  being intended to generate more grant monies,  not to sell working hardware.  Too many folks forget,  or never knew,  that. 

20% efficient perovskite PV cells of 2-5 cm dimension will soon exist,  but not soon enough to go to Mars the first time.  There's usually around 5-25 years between a favorable lab result and a working piece of field equipment.  In today's economic environment,  I'd bet on the 25 years more than the 5 years. 

I think you'd be more realistic looking at silicon PV cells of 6-12% efficiency (6% civilian,  12% military/space and very expensive),  or perhaps the ~5% efficient flexible polymer PV materials.  I'd only look at the polymer if there was some reason to believe a plastic would survive in space conditions.  Most plastics do not do well in vacuum and temperature extremes,  or with harsh radiation. 

GW

Last edited by GW Johnson (2016-07-10 13:27:03)


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#82 2016-08-06 16:21:06

elderflower
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Registered: 2016-06-19
Posts: 521

Re: Power generation on Mars

It seems to have been established recently that water is pretty common on Mars. If it proves to have the same isotopic composition as that reported so far, deuterium will be abundant and can be separated by electrolysis, which I expect  is going to be done anyway, to generate oxygen and hydrogen. This by product heavy water is just what is needed for a Candu or similar reactor. A heavy water moderated reactor can burn Uranium or Thorium fuel with a much lower degree of enrichment than other reactor types. They are not so popular on earth due to the expense of the heavy water that they require and due to their production of tritium which can be used in Hydrogen weapons (and is toxic because of its short half life). With abundant heavy water and the ability to freeze the tritiated waste this should not be a problem on Mars and the risks of shipping fuel from earth would be much reduced by reason of its low enrichment.

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#83 2017-01-14 21:27:42

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 10,527

Re: Power generation on Mars

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#84 2017-11-12 11:12:20

knightdepaix
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Registered: 2014-07-07
Posts: 100

Re: Power generation on Mars

A minute question, does the power generation by current nuclear fission technology on Earth generate lots of neutron in its fission reactions?

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#85 2017-11-12 14:41:56

JoshNH4H
Mod and Martian
From: New York, NY, USA, Earth, Sol
Registered: 2007-07-15
Posts: 2,134
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Re: Power generation on Mars

All nuclear fission energy generates substantial amounts of neutrons


-Josh

If you try to talk to me about cold fusion or propellantless drives I will ignore you.
Mod actions in red

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#86 2017-11-14 11:34:32

elderflower
Member
Registered: 2016-06-19
Posts: 521

Re: Power generation on Mars

Excess neutrons are essential to compensate for losses of neutrons from the reaction. Otherwise the reaction would die down instead of being a chain reaction. The excess of neutrons over losses is absorbed to stabilise the reaction at the desired level so that it neither runs away leading to meltdown, nor dies out from loss of too many neutrons.

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#87 2017-11-14 16:37:17

Antius
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From: Cumbria, UK
Registered: 2007-05-22
Posts: 948

Re: Power generation on Mars

The number of neutrons yielded by fission increases with incident neutron energy.  This is why breeder reactors tend to be fast reactors.

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#88 2017-11-14 17:39:43

kbd512
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Registered: 2015-01-02
Posts: 1,135

Re: Power generation on Mars

If you bury the reactor in the ground, much of the neutron radiation can be attenuated using enough regolith, although gamma remains particularly problematic.  Some shielding is always required to protect electronics and proper shielding is mandatory for personnel to be able to work near an operating reactor.  Some recent work has been done on using metal foams to replace the prototypical mix of high-Z (Pb, W, DU, etc) / low-Z (H, B, Be, etc) value materials to shield against both gamma and neutron radiation, respectively.  The materials are Tungsten impregnated stainless steel foams that apparently weigh no more than plain stainless steel foam.  It's pretty interesting stuff and drastically cuts down on the weight of the shielding.

You can read about it here:

Attenuation efficiency of X-ray and comparison to gamma ray and neutrons in composite metal foams

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#89 2017-11-14 18:26:42

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 10,527

Re: Power generation on Mars

316 L Stainless steel Type is an austenitic chromium-nickel stainless steel containing molybdenum. 
http://www.aksteel.com/pdf/markets_prod … _Sheet.pdf

Found this nicely put together chemistry table with Symbols Used in Nuclear Chemistry http://www.kentchemistry.com/newRT.pdf

I can see getting rid of the Pb (Lead) and W (Tungsten) as that is heavy for the lighter combination of Boron and Beryllium.

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