sci.physics.particle

On Feb 16, 2:54 pm, BradGuth wrote:
> Come on folks, this topic needs as many of those Google/NOVA Usenet
> gold stars as you can muster.
>
> Ion thrusting isn't even my idea, it just needs to get a whole lot
> larger and having a greater cache of those spare/surplus ions to focus
> and accelerate to at least 0.1'c'.
>
> Why not a gigaVolt or even a teraVolt grid differential potential, or
> that of a laser cannon pumped version of using those Rn222 ions as the
> laser plasma gas?
> . - Brad Guth
>
> BradGuth wrote:
> > What if instead of our going with whatever's small, extremely cheap,
> > fast and rad-hard robotic, what if going with larger is nearly always
> > better?
>
> > Perhaps this new and improved topic of "Building Spaceships" for
> > accommodating us frail humans on interstellar treks, and of those
> > multi generation habitat spacecraft being extensively ion thrusted,
> > along with the wizardly help of William Mook and those few of us
> > unafraid of whatever's out there, as such may be a little easier said
> > than done, not to mention folks having to deal with my dyslexic
> > encryption and frequent typos that can't always manage to keep those
> > numbers or terminology half straight.
>
> > Perhaps such a large scale ion thrusted spacecraft isn't quite as
> > insurmountable as we've been told, and it's not that a pair or quad
> > worth of substantial LRBs would not have to help get this rather
> > substantial package off the pad (in modules if need be, and assembled
> > at the moon's L1). However, upon launch and of once reaching the cool
> > upper most atmosphere is where the potential of ion thrusting could
> > start to contribute w/o Radon saturating Earth in the process, and
> > obviously from whatever LEO point onward is where the real potential
> > of ion thrust becomes impressive, especially since this method of
> > electro-rocket thrust can be sustained for as long as the given cache
> > of ions and electrical energy holds out. (with radium->radon there's a
> > failsafe worth of 1600+ years before reaching half-life, so there's
> > never a total lack of those Rn222 alpha/ions, and there's even some
> > electron energy derived from the Radium->Rn breeder reactor)
>
> > Given a sufficient cache of hefty ions and a sufficient onboard supply
> > of electron energy for artificially accelerating and redirecting those
> > ions into a narrow exit trajectory, and if this thrust is the direct
> > result of a given ion flow rate or mass of whatever ion particles per
> > second times the exit velocity squared, as then where's the
> > insurmountable problem, other than your not standing anywhere behind
> > those ion thrusters.
>
> > Radon just so happens to make for a very good cache of substantially
> > massive ions that are already quite active/reactive and supposedly
> > going places as is, at roughly 1.63e7 m/sec. Liquid Radon or LRn222
> > represents a nifty fluid cache of a easily stored concentration of
> > Radon gas (though because of its short half-life it's still very much
> > one of those use it or lose it substances, with possibly an extended
> > life within a near solid 0 K storage), of which I believe this cache
> > of Rn222 can be electrically induced or excited into exiting this ion
> > thruster at a velocity as great as 0.1'c' (perhaps an exit velocity of
> > 0.5'c' is technically doable if we're talking about a radon pumped
> > laser cannon).
>
> > Similar to: http://en.wikipedia.org/wiki/Ion_engines,
> >http://eprints.soton.ac.uk/47966/01/paperColettiMPD.pdf
> > Our lord all-knowing (aka World FactBook) Mook says; "Check it out"
> > Here is how much thrust a rocket engine produces;
> > F =3D mdot * Ve
> > where mdot =3D mass flow rate, as kg/sec
> > Ve =3D exhaust speed m/sec
> > F =3D force (newtons) kg m/sec/sec
>
> > Here is how much power a rocket engine's jet produces
> > P =3D 1/2 * mdot * Ve^2
> > That is, the rate at which energy must be added to the exhaust jet is
> > the kinetic energy of the parts.
> > - - - -
>
> > Of course this is not about any Mook passive alpha particle directing
> > application, instead taking efficiency of the overall electrical and
> > ion tossing system into account (such as thermal energy losses) adds
> > to this existing amount of ion worth via applied electrical and
> > magnetic energy that'll focus and accelerate those ions. So, it is not
> > nearly as simple to express as one as Mook might suggest.
>
> > However, at the notion of our getting rid of this initial tonne worth
> > of our liquid cache of LRn222, at the ion mass flow rate of 1 kg/s,
> > whereas the kinetic power or energy worth of thrust supposedly
> > becomes:
>
> > If the 1 kg/s flow of Rn ions and the exit Ve were made as great as
> > 10%'c' =3D 3e7 m/s
>
> > P =3D .5 * 9e14 =3D 4.5e14 kgf
>
> > At utilizing this ion exit velocity of 0.1'c' (3e7 m/s)
> > A metric tonne of LRn that'll essentially become just plain old Rn gas
> > of pure Rn222 ions, at using up one kg/s =3D 1000 seconds worth of
> > creating 4.5e14 kgf, of which this substance would push a 4.5e12 kg
> > (4.5 gigatonne) spacecraft at 100 gee in relationship to the gravity
> > at the surface of Earth.
>
> > At the more realistic ion exit velocity of 1% light speed is
> > 0.01'c' (3e6 m/s)
> > A metric tonne of LRn that'll essentially become just plain old Rn gas
> > of pure Rn222 ions, at using one kg/s =3D 1000 seconds worth of 4.5e12
> > kgf, of which would push a 4.5e10 kg (45 megatonne) spacecraft at 100
> > gee in relationship to gravity at the surface of Earth.
>
> > Of course the 45 megatonne spacecraft isn't hardly any more likely
> > than human DNA or whatever spacecraft structurally surviving 100 gee.
>
> > So, to start off with we'd likely have ourselves a whole lot smaller
> > than 45 megatonne spacecraft, such as perhaps only as great as 4.5
> > megatonnes that'll exit away from Earth at perhaps as great as 10 gee,
> > then once 10r (63,730 km and just 1% Earth gravity) is reached,
> > whereas this is when the ion exit velocity could be safely punched up
> > from 0.001'c' to 0.01'c', and eventually the maximum of 0.1'c' could
> > be applied to as little as using a gram of Rn222 per second, because
> > at 0.1'c' or better exit velocity is where you really do not require
> > all that much mass flow per second.
>
> > 0.1% light speed is 0.001'c' =3D 3e5 m/s
>
> > 1 kg/sec at 3e5 m/s =3D .5 * 9e10 =3D 4.5e10 kgf
>
> > 4.5e10 kgf would push a 4.5e6 tonne spacecraft along at 10 gee
>
> > Using a gram/sec:
> > 4.5e7 kgf would push a 4.5e6 tonne spacecraft along at 0.1 gee
>
> > I believe that 1000 seconds of 10 gee acceleration is worth 78.4 km/s,
> > though of course we'd be past the 10r of Earth within the first 600
> > seconds, and thereby able to ion whiz past that 78.4 km/s mark like it
> > was standing still.
>
> > This next part is often where my math takes yet another nose dive, but
> > since I do not have the fly-by-rocket software and none others that
> > claim as always being all-knowing are seldom willing to share, is why
> > I'll just have to make do, especially since even the warm and fuzzy
> > likes of Mook always takes the lowest road possible in order diminish
> > and/or disqualify whatever isn't of his idea to start off with,
> > excluding just enough of the good stuff in order to foil any further
> > thought process.
>
> > The required energy for a given thousand seconds worth of accelerating
> > those Rn222 ions up to 3e5 m/s isn't exactly insignificant, demanding
> > perhaps at least 245.2 GW.h (8.826 e14 J) for accommodating all 16.7
> > minutes worth of ion thrust. However, due to the overall efficiency
> > of this energy transfer into accelerating those Rn ions is why it'll
> > more than likely demand somewhat greater energy for accomplishing this
> > task of tossing out the entire tonne worth those Rn222 alpha ions at
> > the rate of one kg/s, even if that's initially accomplished at this
> > minimal 0.001"c". However, since the existing Rn alpha particle
> > velocity is already self motivated at 1.6e7 m/s(.054'c'), perhaps
> > along with given another 5.6 MeV boost is where the required energy
> > can be limited as to whatever's necessary for accomplishing a good
> > exit focus or creating that laser cannon like beam, in which case the
> > required ion thruster energy could become relatively minimal for
> > accomplishing an impressive exit ion velocity of 3.26e7 m/s.
>
> > At times this spacecraft is going to require a hole lot more
> > electrical energy than any cache of Radium to Radon reactor could
> > manage at 32 kw/Ra tonne, or even 320 kw/breeder Ra tonne. However,
> > at a gross spacecraft mass of 4.5e6 tonnes, there's no problem with
> > incorporating an h2o2/aluminum fuel cell of 100 GW.h capacity, or
> > accommodating whatever Lithium nanotube ion battery storage, nuclear
> > reactors or fusion alternatives.
>
> > Once trekking off into interstellar space, and especially upon getting
> > this craft past our nearest interstellar L1, and of the other gravity
> > pulling us towards the likes of the relatively massive Sirius star/
> > solar system that we're already in blueshift as headed towards Sirius,
> > as this is when as little as a mdot microgram/sec of Rn222 at the exit
> > velocity of 0.2'c' would be more than sufficient ion thrust for
> > continually accelerating this 4.5e6 tonne spacecraft towards the
> > gravity pull of Sirius.
>
> > For a one microgram/sec of Rn222 mdot at 0.2'c' example:
> > P =3D .5e-9 * 3.6e15 =3D 1.5e6 kgf (1,500 tonnes/s of thrust, or in th=
is
> > case 0.000333 gee)
>
> > The next problem gets down to the business of continually building up
> > another cache of LRn from the Ra->Rn breeder reactor while on the fly,
> > on behalf of that pesky matter of our having to ion retrothrust long
> > before overshooting the intended target. At 4.5e9 kg, stopping this
> > sucker that's by now going like a bat out of hell (possibly having
> > reached 0.1'c') is going to take some doings. Of course, there would
> > be generations of new and improved minds onboard in order to figure
> > most of this out before arriving into the Sirius star/solar system,
> > not to mention whatever could have been transmitted from Earth over
> > the past century.
>
> > BTW, at this point of topic argument sake,
>
> ...
>
> read more =BB

What! no takers? No ion expertise? No guts? (must be another one of
those pesky MIB enforced nondisclosure things)
=2E - BG