NASA Successfully Tests Ion Engine

On Sat, 29 Nov 2003 07:58:47 -0700
\(formerly\)" dlzc1.cox@net wrote:

I'd worry about "selectively ionizing" a molecule for propulsion. Since the number of electrons stripped off provides the handles for
accelerating the mass, the more electrons removed means the faster you
can accelerate the molecule. But the more electrons you remove the
weaker (or smaller) the molecule fractions become. So your C60
becomes just 60C, and you are back to accelerating a bunch of light
nucleii.

C_60 is pretty stable, though, and, like any molecule, will hold on tighter to its remaining electrons once it's already lost some. Some quick googling suggests C_60 can lose at least 3 electrons without breaking up, but will start shedding C_2 ions at some point after that. I don't know much about ion drives, but I'd think that'd be good enough.

What I'd be more worried about is carbon buildup on the grids. If even a small fraction of the molecules sticks to the charged surfaces (and those C_2 fragments are likely to be particularly sticky) the resulting soot buildup might well become a problem over time.

--
Ilmari Karonen
If replying by e-mail, please replace ".invalid" with ".net" in address.

Dear Ilmari Karonen:

"Ilmari Karonen" wrote in message
...
On Sat, 29 Nov 2003 07:58:47 -0700
\(formerly\)" dlzc1.cox@net wrote:

I'd worry about "selectively ionizing" a molecule for propulsion.
Since the number of electrons stripped off provides the handles for
accelerating the mass, the more electrons removed means the faster you
can accelerate the molecule. But the more electrons you remove the
weaker (or smaller) the molecule fractions become. So your C60
becomes just 60C, and you are back to accelerating a bunch of light
nucleii.

C_60 is pretty stable, though, and, like any molecule, will hold on
tighter
to its remaining electrons once it's already lost some. Some quick
googling suggests C_60 can lose at least 3 electrons without breaking up,
but will start shedding C_2 ions at some point after that. I don't know
much
about ion drives, but I'd think that'd be good enough.

I wouldn't expect that to be of much help. That is a lot of mass, and very
little net charge. The accelerator path would have to be "long".

What I'd be more worried about is carbon buildup on the grids. If even a
small fraction of the molecules sticks to the charged surfaces (and those
C_2 fragments are likely to be particularly sticky) the resulting soot
buildup
might well become a problem over time.

If you strip electrons, just leave a net positive charge on the "nozzle"
(or an AC with a positive bias to invoke any diamagnetism).

I would wonder if you couldn't *add* a few electrons, to either C60, or
some long polymer chain. In fact, I seem to recall that some ions were
trapped *inside* C60 (how they'd stay ions seems the $64 question). In
other words, shoot the cat and then the rubber rod out the back...

David A. Smith

In article ,
Ilmari Karonen wrote:
C_60 is pretty stable, though, and, like any molecule, will hold on
tighter to its remaining electrons once it's already lost some. Some
quick googling suggests C_60 can lose at least 3 electrons without
breaking up...

Unfortunately, preliminary experiments with it for ion propulsion were not
favorable -- in the sort of environment needed to quickly ionize significant
flows of material, it's not stable *enough*. The more determined folks have
not entirely given up, but it's not going to be easy.
--
MOST launched 30 June; first light, 29 July; 5arcsec | Henry Spencer
pointing, 10 Sept; first science, early Oct; all well. |

In article FFyyb.24793$Bk1.5331@fed1read05,
\(formerly\) dlzc1.cox@net wrote:
I would wonder if you couldn't *add* a few electrons, to either C60, or
some long polymer chain.

Unfortunately, good negative-ion sources are even harder to build than
positive-ion sources.
--
MOST launched 30 June; first light, 29 July; 5arcsec | Henry Spencer
pointing, 10 Sept; first science, early Oct; all well. |

Henry Spencer opined

In article ,
Ilmari Karonen wrote:
C_60 is pretty stable, though, and, like any molecule, will hold on
tighter to its remaining electrons once it's already lost some. Some
quick googling suggests C_60 can lose at least 3 electrons without
breaking up...

Unfortunately, preliminary experiments with it for ion propulsion were not
favorable -- in the sort of environment needed to quickly ionize significant
flows of material, it's not stable *enough*. The more determined folks have
not entirely given up, but it's not going to be easy.

Given all the symmetries with the C60 molecule, could a tuned laser do the
ionization?

-ash
for assistance dial MYCROFTXXX

"Ash Wyllie" writes:

Henry Spencer opined

In article ,
Ilmari Karonen wrote:
C_60 is pretty stable, though, and, like any molecule, will hold on
tighter to its remaining electrons once it's already lost some. Some
quick googling suggests C_60 can lose at least 3 electrons without
breaking up...

Unfortunately, preliminary experiments with it for ion propulsion were not
favorable -- in the sort of environment needed to quickly ionize significant
flows of material, it's not stable *enough*. The more determined folks have
not entirely given up, but it's not going to be easy.

Given all the symmetries with the C60 molecule, could a tuned laser do the
ionization?


Yes, but it would almost certainly have to be a tuned ultraviolet laser,
and those are pretty hard to come by. Harder still if you demand even
five percent efficiency, which you need to be competitive with the more
conventional propellant ionization systems.

Two-photon processes could theoretically get you ionization using only
tuned visible lasers, but such processes are inherently inefficient,
demand very high laser intensities, and are generally not worth the
bother unless the universe obliges you with a metastable state halfway
between ground and first ionization.


--
*John Schilling * "Anything worth doing, *
*Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" *
*Chief Scientist & General Partner * -13th Rule of Acquisition *
*White Elephant Research, LLC * "There is no substitute *
* for success" *
*661-951-9107 or 661-275-6795 * -58th Rule of Acquisition *

On Sun, 30 Nov 2003 15:12:10 -0800, pervect
wrote:

On Sun, 30 Nov 2003 08:41:52 -0800, Mary Shafer
wrote:

Can you get enough energy out of a grape that grapes are usable?
Would you grow grapes in space for long voyages? Can the spent grapes
be used to make wine with? Is there a market for space wine?
--
Mary Shafer Retired aerospace research engineer

So, are you by any chance considering a new career as a writer of
satire? Or perhaps a TV ancherperson (or their scriptwriter).

:-)

Just anticipating. What goes around, comes around, after having
undergone a rich and mysterious sea change. Six months from now, this
subject line will reappear with a garbled version that does use grape
juice or grape seeds or something. And thanks to me, we'll all know
what questions to ask the proponent.

I could never be a writer for an anchorperson; I'd be fired after
about a week. Cf. "Chuckles the Clown Is Dead", an episode of the
Mary Tyler Moore Show. Ted Baxter is, as far as I can tell, smarter
than many anchorpersons, by the way. Or cf. "Dirty Laundry" by some
group or another.

Mary

--
Mary Shafer Retired aerospace research engineer

On Sun, 30 Nov 2003 10:00:43 -0700, \(formerly\)"
dlzc1.cox@net wrote:

Dear Mary Shafer:

"Mary Shafer" wrote in message
...
On Fri, 28 Nov 2003 20:33:25 GMT, (Henry Spencer)
...
There are already ion thrusters that use microwaves for ionization, and
also some that use lower-frequency radio waves. No actual thruster
that
I'm aware of uses lasers or X-rays.

How many use grapes?

You probably already know this, and are being funny.

Well, trying to be, at any rate.

The thread title
refers to how a (presumably wet) grape shoots out from between your fingers
when you try to squeeze it.

I think it's a reference to how some grapes, like those native to the
US, slip out of their skins when squeezed. At least, I've heard a lot
about how easy it is to "peel" such grapes that way. I've never seen
it, though. Every grape I've ever eaten had its skin stuck on quite
tightly.

I'd have said "watermelon seed drive", myself. You can get some real
range with them, squeezing them.

Mary

--
Mary Shafer Retired aerospace research engineer

"Mary Shafer" wrote in message
...
On Sun, 30 Nov 2003 10:00:43 -0700, \(formerly\)"
dlzc1.cox@net wrote:

Dear Mary Shafer:

"Mary Shafer" wrote in message
...
On Fri, 28 Nov 2003 20:33:25 GMT, (Henry Spencer)
...
There are already ion thrusters that use microwaves for ionization,
and
also some that use lower-frequency radio waves. No actual thruster
that
I'm aware of uses lasers or X-rays.

How many use grapes?

You probably already know this, and are being funny.

Well, trying to be, at any rate.

The thread title
refers to how a (presumably wet) grape shoots out from between your
fingers
when you try to squeeze it.

I think it's a reference to how some grapes, like those native to the
US, slip out of their skins when squeezed. At least, I've heard a lot
about how easy it is to "peel" such grapes that way. I've never seen
it, though. Every grape I've ever eaten had its skin stuck on quite
tightly.

I'd have said "watermelon seed drive", myself. You can get some real
range with them, squeezing them.

Mary

I think its more refering to the effect you can get when you place a very
carefully split grape in a microwave..poof, instant ball of "plasma"

http://c3po.barnesos.net/homepage/lpl/grapeplasma/

Phoenix-D

"Phoenix-D" wrote in message
news:CfUyb.51559$kl6.39499@fed1read03...

"Mary Shafer" wrote in message
...
On Sun, 30 Nov 2003 10:00:43 -0700, \(formerly\)"
dlzc1.cox@net wrote:

Dear Mary Shafer:

"Mary Shafer" wrote in message
...
On Fri, 28 Nov 2003 20:33:25 GMT, (Henry
Spencer)
...
There are already ion thrusters that use microwaves for
ionization,
and
also some that use lower-frequency radio waves. No actual
thruster
that
I'm aware of uses lasers or X-rays.

How many use grapes?

You probably already know this, and are being funny.

Well, trying to be, at any rate.

The thread title
refers to how a (presumably wet) grape shoots out from between your
fingers
when you try to squeeze it.

I think it's a reference to how some grapes, like those native to the
US, slip out of their skins when squeezed. At least, I've heard a lot
about how easy it is to "peel" such grapes that way. I've never seen
it, though. Every grape I've ever eaten had its skin stuck on quite
tightly.

I'd have said "watermelon seed drive", myself. You can get some real
range with them, squeezing them.

Mary

I think its more refering to the effect you can get when you place a very
carefully split grape in a microwave..poof, instant ball of "plasma"

http://c3po.barnesos.net/homepage/lpl/grapeplasma/

Phoenix-D



I tried to make my favorite dish of Chicken Livers
in the nuker and I suggest it not be attempted by others..