Project FOOF with FF-DPFs

[vansig]

zapkitty wrote:
The limitation, of course, will be that you can only run the DPF intermittently.

Let the station heat rejection system chill the heat sink back down, and repeat.

But, unlike my previous 1 MWe low-power concept, during this power cycle you can run the reactor at whatever power setting gives the greatest efficiency.

Full-tilt boogie… be it 5 MWe or 11 MWe.

bursts of large power could have advantages, for placing your delta-v closer to where you need it. but i don’t know if the gain from that would cover the the mass penalty.

contrast this with: running radiators hotter lets you make them smaller. and heat rejection by venting plasma into the exhaust nozzle might cover all of it: giving extra thrust, at lower Isp, with all of the needed heat rejection.

[zapkitty]

Apparently Lerner-hakase is going to be on the podcast Space Show.

http://www.facebook.com/pages/Focus-Fusion-Society/205597630257

Given his recent hints that electrodes may require changeouts after 30 days at 5 MWe and that units operating at less than 5 MWe may be difficult to implement… it will be interesting to hear how he thinks FFs will be applicable to space under those conditions.

Hopefully by then he’ll be up LDR and LSR type radiator systems 🙂

[zapkitty]

zapkitty wrote: Apparently Lerner-hakase is going to be on the podcast Space Show.

Hereafter follows my personal, condensed, and intermittently reordered version of what Lerner-hakase talked about on The Space Show. In my next post I’ll discuss the numbers that were tossed out as some of them seem to be… errors?

Warning: The following is extremely zap-centric stream-of-semi-consciousness and may or may not have some hitherto undefined relationship with what Lerner-hakase may or may not have actually said on the program 🙂

(comments in parentheses are all mine and you can’t have them)

What I think Lerner said:

State of fusion: we’ve already had the LPP updates here and nothing new on the other contenders was discussed.

As for toks… lots of ostriches with heads in sand seemingly unaware that in that position their necks are stretched out very far by now.

(With apologies to Brewer and Shipley: “One tok over the line…” )

… will the fusion ban at NASA ever be lifted?

When pB&j tests start LPP won’t do much talking until iron-clad proof of boron fusion is secured.

LPP Team forgoes “breakeven” phraseology for “scientific feasibility”. That term will mean that they’ve proven that they can generate sufficient excess power to power a generator when generators are ready. Actual generator engineering will be the next step after feasibility is proven.

LPP patents will protect investors but will not enable an LPP fusion monopoly… but the investors should do well.

(very well I’d think)

Callers to the show asked about FF space applications, is FF a Polywell, why pB&j and not D+D…

Space applications:

minimum pulse rate? cooling boron might plate out between pulses?

(would be bad as plated boron wouldn’t easily be removed short of an overhaul – what’s the fuel pre-heater wattage?)

FF best as in-space drive but could power a MHD launcher w/ fuel only 1/10th mass of payload,

Talked about FF as better for robotic missions without mention of electrode core changeout…

(that would mean a disposable stage or a tug that returns for reuse…. … or multiple staged cores? contact mad scientist central 8) )

Talked about FF as power supply for bases, Mars base talk.

(what about in situ reforming of electrodes?)

[zapkitty]

Here are some numbers that Lerner-hakase tossed out during his Space Show appearance and my patella-twitching responses to a few of them are in parantheses:

50 kj pulse = 500 hz

(isn’t this supposed to be about 10 kj now? 50 kj at 500 hz gives us 25 megawtfs… )

5 mw genset @ 3 tons and 2 meters wide

(Unshielded mass? He uses 3 tons as current mass of LPPX-1 but then uses this # for mass for FFs in general use… and they will need shielding )

output 1/3 x-rays – caught by PV with thousands layers of metal
2/3 beam !

(this needs confirmed please)

[Ivy Matt]

zapkitty wrote: why pB&j and not D+D…

I believe that question was actually about why not p+Li7, p+F, or D+T. Lerner didn’t mention it, but tritium is rather difficult to get hold of, as it’s a highly-regulated (and dangerous) substance. Of course, you can always produce it yourself. But either way, it doesn’t make sense to use tritium for fusion research unless you have no hope of achieving breakeven with D+D, and you’re quite confident you’re close to breakeven with D+T. Even the tokamak people almost never use tritium in their experiments. After ITER is complete and well-tested (which should be some time between 2026 and never), then they’ll start using deuterium-tritium fuel.

[jamesr]

The first few years of ITER operation will be with just plain old H, not even D. As they want to avoid even the small amount of tritium made in D+D reactions contaminating everything and making it impossible for people to go in and maintain things. As soon as they start using even deuterium everything will have to be done remotely by robots

[vansig]

zapkitty wrote:
Talked about FF as better for robotic missions without mention of electrode core changeout…

(that would mean a disposable stage or a tug that returns for reuse…. … or multiple staged cores? contact mad scientist central 8) )

Talked about FF as power supply for bases, Mars base talk.

(what about in situ reforming of electrodes?)

That’s where the general-purpose orbital factory comes in.

Here are some numbers that Lerner-hakase tossed out during his Space Show appearance and my patella-twitching responses to a few of them are in parantheses:

50 kj pulse = 500 hz

(isn’t this supposed to be about 10 kj now? 50 kj at 500 hz gives us 25 megawtfs… )

nominal 5 to 20 MW has been talked about for some time.. with possible impact on cooling and anode wear.

5 mw genset @ 3 tons and 2 meters wide

(Unshielded mass? He uses 3 tons as current mass of LPPX-1 but then uses this # for mass for FFs in general use… and they will need shielding )

output 1/3 x-rays – caught by PV with thousands layers of metal
2/3 beam !

(this needs confirmed please)

current LPPX-1 has shielding. maybe the 3 tons includes that?

[zapkitty]

vansig wrote:

Here are some numbers that Lerner-hakase tossed out during his Space Show appearance and my patella-twitching responses to a few of them are in parantheses:

50 kj pulse = 500 hz

(isn’t this supposed to be about 10 kj now? 50 kj at 500 hz gives us 25 megawtfs… )

nominal 5 to 20 MW has been talked about for some time.. with possible impact on cooling and anode wear.

… but a 5 mw FF is what he discusses and is the current proposed baseline, correct?

vansig wrote:

5 mw genset @ 3 tons and 2 meters wide

(Unshielded mass? He uses 3 tons as current mass of LPPX-1 but then uses this # for mass for FFs in general use… and they will need shielding )

current LPPX-1 has shielding. maybe the 3 tons includes that?

… it does? I thought that LPPX-1 had no integral rad shielding and it’s the room it’s in that has the shielding.

Minimum mass spherical shielding according to the LPP descriptions would be still be well over 4 tons.

zapkitty wrote: output =

1/3 x-rays – caught by PV with thousands layers of metal

2/3 beam

(this needs confirmed please)

This is also a puzzle. Was previously stated to be approx 50/50.

While in theory it makes no difference in total output it makes a big difference in application… and in applications.

Also inspires daydreaming of brem suppression in excess of expectations 🙂

[Ivy Matt]

The most significant points to me were:

1) The article for Physical Review Letters is currently being worked on, and will hopefully be submitted this month. It will discuss high ion energies and the evidence that the fusion neutrons are coming from the plasmoid.
2) Testing with hydrogen-boron is hoped to begin sometime this summer. (Given the delays so far, and what remains to be done with deuterium and nitrogen, I had expected this to happen no sooner than the fall. I still half-expect it to take that long, at least.)
3) (As reported by zapkitty:) Once hydrogen-boron is being burned, it sounds like we won’t hear much publicly (at least concerning specific numbers) until LPP is ready to publish.

I don’t recall hearing any updates on the status of the FF-1 upgrade, or specifics on what testing will be done in the next few months before the switch to hydrogen-boron.

[vansig]

Ivy Matt wrote:
1) The article for Physical Review Letters is currently being worked on, and will hopefully be submitted this month. It will discuss high ion energies and the evidence that the fusion neutrons are coming from the plasmoid.

Can we have the full citation for this article?

[Author]

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