Chapter 6
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John Gallagher
- Posts: 20
- Joined: Sat May 10, 2008 3:35 pm
- Location: Winter Park Florida
Typo you say? NBF just said the Dragon has a new cat smell. That's a typo. KW/MW ia a late night senior moment. Burn % etc is important for sure but the operational pressure is the real driver as far as the pumping system goes. Sorry that I don't know this but it seems that anything over e-7 Atm and your electron/ion mean free path is much smaller than the chamber dimensions. How can you generate a virtual cathode under these conditions?
Re: chaper 6 vacuum pumping system
The number I worked out a few years back was .5 Kg/day for 100 MW. One of us has dropped a decimal point.John Gallagher wrote:5kg of boron/hr for 100meg's ! I was wondering what pressure this thing may run at. Hydrogen and helium are real bears to pump. At 1 micron pressure you are looking at a million or two liters a second pump speed. One big diffusion pump! The backing pumps would be interesting also as turbo and diffusion pumps tend to have compression ratios under a thousand for these gases. If these were operating at a lower pressure they would have to be scaled by the same ratio. A diff pump would have backstreaming problems at 1 micron and a turbo would have cooling problems. Etc etc. This is not your father's vacuum system!
Engineering is the art of making what you want from what you can get at a profit.
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John Gallagher
- Posts: 20
- Joined: Sat May 10, 2008 3:35 pm
- Location: Winter Park Florida
Using 8.7 Mev per Boron 11 atom X 1.6022E-19 joules/ev you get 13.93914E-13 joules/B. 100 Meg joules/Hr(3.6E11) over 13.93914E-13 gives 2.58E23 boron atoms/Hr. Division by 6.02E23 atoms/mole gives .428 moles or 4.714 gms/Hr ( 113.136 gms/day). A pain to think about this way but a check on decimal point position. So tell me what pressure are these things speculated to operate at?
Re: chaper 6 vacuum pumping system
So 0.347 g/min for 100 MW or, assuming linear scaling,MSimon wrote:The number I worked out a few years back was .5 Kg/day for 100 MW.
3.47 g/min for 1 GW, or
17.4 g/min for 5GW, or
174 g for a 10 minute boost to orbit (1 Mlb-class vehicle).
For pre/post-orbit hover using superconducting electric fans, add to that the minutes spent hovering times 1.74 g/min. Hover power is about 1/10 the orbit boost power for a 1 Mlb vehicle. Hover to REB-start transition (Mach 0 to 2.5) is neglected here. Along with a few other minor things.
Re: chaper 6 vacuum pumping system
Previous 5 gm/hr was for gross, unconverted kinetic energy. On the other hand, 100MW context as used by MSimon is unclear. Is it MWe? Net? Gross? If it is MWe Net, then the assumptions would include auxiliary power for vacuum pumps, conversion efficiency to electric, Polywell device losses, etc, and could be almost consistent. If not, perhaps there is some issue with energy / fusion event, or all of the above (context + ev/B fusion event). Just trying to avoid apples and water mellon thread disfunction...MSimon wrote:The number I worked out a few years back was .5 Kg/day for 100 MW. One of us has dropped a decimal point.
Best regards, as always...
PS to KitemanSA, talk-polywell posts are so many, and the threads all seem to wander (a lot) after a bit, perhaps you might consider putting together a prototype B plant energy balance, with vacuum pump numbers, etc. for part of the FAQ project? There seems to be enough retirees now...
Counting the days to commercial fusion. It is not that long now.
I did that around here years ago. I'm now on to other things. Like computers with 4 working pins (and two for power). It is a 16 bit machine with an 8 bit internal bus. Kind of like a Super 8 (or ARM) in functional layout. One K of ROM and 32 bytes of RAM (not counting registers). Cute. And 68 cents in onesies.PS to KitemanSA, talk-polywell posts are so many, and the threads all seem to wander (a lot) after a bit, perhaps you might consider putting together a prototype B plant energy balance, with vacuum pump numbers, etc. for part of the FAQ project? There seems to be enough retirees now...
Engineering is the art of making what you want from what you can get at a profit.
http://repository.unm.edu/bitstream/han ... sequence=1Robthebob wrote:i must be out of the circle, why is it chapter 6?
Engineering is the art of making what you want from what you can get at a profit.
Link to the needle in this haystack?MSimon wrote:I did that around here years ago.PS to KitemanSA, talk-polywell posts are so many, and the threads all seem to wander (a lot) after a bit, perhaps you might consider putting together a prototype B plant energy balance, with vacuum pump numbers, etc. for part of the FAQ project? There seems to be enough retirees now...
Counting the days to commercial fusion. It is not that long now.
Good luck with that.mvanwink5 wrote:Link to the needle in this haystack?MSimon wrote:I did that around here years ago.PS to KitemanSA, talk-polywell posts are so many, and the threads all seem to wander (a lot) after a bit, perhaps you might consider putting together a prototype B plant energy balance, with vacuum pump numbers, etc. for part of the FAQ project? There seems to be enough retirees now...
Engineering is the art of making what you want from what you can get at a profit.
WB-8 Plasma Decay Rate
Is there anyone on this forum with the physics chops (and time to spare) to determine anything useful from figure 6-6 on pg 70 of the thesis report, which is the plot of density decay with plasma injection turned off. (It's certainly not me!)
It shows the plasma density losing one order of magnitude of density in 0.2 ms.
The last sentence of this page says:
'In addition to the peak density, the rate of decay in this region will give us a good idea of how well the plasma is being confined.'
So, as one of the things we have been wondering about is plasma confinement, it seems to me that this is 'real data' on confinement, which should be of interest or discussion.
Anyone?
It shows the plasma density losing one order of magnitude of density in 0.2 ms.
The last sentence of this page says:
'In addition to the peak density, the rate of decay in this region will give us a good idea of how well the plasma is being confined.'
So, as one of the things we have been wondering about is plasma confinement, it seems to me that this is 'real data' on confinement, which should be of interest or discussion.
Anyone?
There are strange things done in the midnight sun....
Actually, the shutting off of the plasma injection was kind of the point of that figure, as I understand it. When operating at as close to steady state as they operate the device, they shut off the 'plasma source' (they don't say what it is), and monitored the loss of density of the plasma.
90% of the plasma was gone within the 0.2 ms of stopping plasma injection.
My question is, does that tell us anything about confinement or other metrics of the device if the dwell time in the machine is less than 0.2 ms for a typical particle? Or am I misinterpreting that figure?
90% of the plasma was gone within the 0.2 ms of stopping plasma injection.
My question is, does that tell us anything about confinement or other metrics of the device if the dwell time in the machine is less than 0.2 ms for a typical particle? Or am I misinterpreting that figure?
There are strange things done in the midnight sun....