[vansig]

I don’t get that, at all. drilling down into the debate reaches Donald E. Scott’s abstract, here
http://ecolloq.gsfc.nasa.gov/archive/2009-Spring/announce.scott.html
which says,
“The presentation attempts to motivate the realization that ‘new science’ should not be invoked unless and until all aspects of what we already know, including plasma physics and basic electromagnetism, have been exhaustively applied in the investigation of what appear to be astronomical anomalies.”

An adequate layman’s view of the term ‘magnetic reconnection’ is at http://en.wikipedia.org/wiki/Magnetic_reconnection
which has
“Solar flares, the largest explosions in the solar system, may involve the reconnection of large systems of magnetic flux on the Sun, releasing, in minutes, energy that has been stored in the magnetic field over a period of hours to days. Magnetic reconnection in Earth’s magnetosphere is one of the mechanisms responsible for the aurora, and it is important to the science of controlled nuclear fusion because it is one mechanism preventing magnetic confinement of the fusion fuel.”

I see no controversy there. If it were pseudo-science, I’d expect to see objections in that article

[vansig]

So, take an area of ocean 2500 – 5000 km², depleted of phytoplankton, and fertilize with a mix of 100 parts volcanic ash to 1 part iron sulphate, and monitor it over a decade. if the ratio of 300,000:1 above is correct, then you’ll need 333 kt of fertilizer to yield your 1 Gt CO2 sequestration.

[vansig]

1 Gt CO2 is equivalent to 2.3e13 mol of native carbon, (as soot).

Sequestration in this form is possible because it’s biologically inert. Standard enthalpy change of formation for CO2 is -393.5 kJ/mol, so converting the whole 1 Gt CO2 corresponds to 8.9e18 J.

Assuming ~10% efficiency, this would take 10 years at 283 GW power, producing 0.27 Gt carbon and 0.73 Gt O2 as by-product.
Your mileage may vary.

If that wins the prize, that’s $.09 per kW·decade. Not a really great ROI for a fusion-based scheme.

I say mother Nature should definitely be involved.

[vansig]

vansig wrote:
“Park County has a predicted average indoor radon screening level greater than 4 pCi/L (pico curies per liter)”
— http://www.city-data.com/city/Yellowstone-National-Park-Wyoming.html#ixzz0nqzNO5OD

4 pCi/L equals 148 Bq/m³, and
150 Bq/m³ is the EPA maximum before mitigation is required. So, yes it’s entirely plausible that radiation levels at Yellowstone are higher.

[vansig]

I’m not advocating cutting corners; but rather adding to capabilities at relatively low incremental cost. Modern concepts that appear to work include multi-purpose missions: involving both science and commercial interests, and maximizing what you can still accomplish when things go wrong.

If building a proper space station must be done before an interplanetary supply tug, then so be it. It’d be frustrating if ISS cannot be that station, but i do see your point about ongoing research agreements among the partner nations.

I totally agree that so many of these things, radiators and support technologies, radiation countermeasures, ships assembled in space,
should have occurred decades ago.

it seems to me, that swivels and hinges, and the motors to drive them, are low tech, low cost, and add a lot of capability.

[vansig]

White says it is important to pursue this project in addition to other approaches to fusion. “With our present knowledge it is very risky to commit the program to a single track reactor development — our knowledge is still in flux,” he says.

it is good to see people promote alternative approaches as well, instead of gobble up money.

[vansig]

i don’t see how this game will help to get anything real done.

[vansig]

digh wrote: Is Yellowstone National park decidedly more radioactive?

dont know. but, radon gas release seems to be associated with volcanic eruption:
http://www.nature.com/nature/journal/v288/n5786/abs/288074a0.html
http://en.wikipedia.org/wiki/Taal_Volcano
http://www.springerlink.com/content/272381601455451j/
http://adsabs.harvard.edu/abs/2007AGUFM.V11C0751L

and indoor radon levels at yellowstone are available

“Park County has a predicted average indoor radon screening level greater than 4 pCi/L (pico curies per liter)”
— http://www.city-data.com/city/Yellowstone-National-Park-Wyoming.html#ixzz0nqzNO5OD

[vansig]

The decay chains of U-238 and Th-232 produce electron anti-neutrinos. These are the geo-neutrinos so-hotly disputed in this thread.
But the background level of anti-neutrinos is mainly due to beta decays in nuclear reactors. These may be detected via the inverse beta decay reaction, at a threshold of 1.8 MeV.

In fact i think a directional detector for electron anti-neutrinos is possible, because the “delayed coincidence signature” should indicate momentum, but i’m not sure whether this is resolved in current detectors.
— http://en.wikipedia.org/wiki/KamLAND

Yes, you’ll be detecting a very small number of neutrinos. Most neutrinos passing through the Earth emanate from the Sun, (and trillions pass through the human body each second). and there are also cosmic sources.

[vansig]

For testing only, yes, mounting them opposite would be appropriate.
But, VASIMR engines are due to be tested at ISS soon, arent they? Provided that they work as expected, turning this module into a useful orbit to orbit transport vehicle, (perhaps LEO to LLO and return, with big payloads?) would be the first thing I’d want to do.

It would seem to be a no-brainer to mount hinges and swivel points, and begin operation.

if memory serves, VASIMR VX-200 are ~300 kg each; 80 tonnes of propellant is plenty for pulling bulk supplies to/from lunar orbit.

[vansig]

Yes. It might look like this IR – UV PV cell, recently reported.
http://www.physorg.com/news188637189.html

I wonder if this works as well when x-rays scatter instead of being absorbed?

[vansig]

ok, brainstorming here…

refrigerant
isnt ammonia the more common coolant in space?
i hear that helium would be used to cool the DPF anode?

VASIMR
is the shape realistic?
pictures i’ve seen show the accelerators as longer cylinders

xenon propellant tank for VASIMR?

if opposing nozzles, then each VASIMR engine would connect at about the centre of mass?

can the VASIMR nozzles be positioned?
if they hinge/twist at or near the station’s centre of mass, then they could be
positioned quickly and effectively for acceleration in any direction

mass of the modules?

total station mass?

[vansig]

You could reduce the exhaust velocity of the alphas by bleeding off energy from them with the coil, but that doesn’t trade off Isp for thrust in the same way that VASIMR does. The other way is to collide the alphas with some of the unburnt plasma.

[vansig]

zapkitty wrote: …. and I’d thought that FFDPFs had 50% of their watts electric come put as watts thermal…
… which would give your classic 5 megawatt FFDPF an additional 2.5 megawatts thermal (to use, if on the ground… to contend with, if on orbit…)
… is that ratio incorrect? Or has it changed?

If i remember correctly, Eric said we can expect ~50% system efficiency. Extraction of electric power from the fusion products and xrays is ~80%, but you must factor in the yield, and subtract the power needed to run the next shot. That’s for electricty generation.

For propulsion, the alpha beam and unburnt fuel goes directly to exhaust.

[vansig]

zapkitty wrote: … btw if the FFDPF can actually be run at a helium outlet temp of 627c that would be very useful to know… 😉

To prevent it from being vapourized, the anode must be kept cool. Beryllium melts at 1278 °C. If you can eliminate ablation, you can operate at higher temperatures for longer.

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