sci.physics.particle

Remember, wherever there's Radon(Rn222) to behold, there's a great
deal of Radium(Ra226) nearby, and of wherever there's Ra226 is where
there's an ongoing 1600+ half-year life process of decay that's
continually producing said Rn222. So, by all honest accounting, Earth
is not exactly shy of its fair share of Ra226, of which can be
gathered up and utilized for the breeder decay reactions of creating
Rn222 or even of creating LRn222.

http://www.iisc.ernet.in/currsci/jun252002/1423.pdf
Radon and helium monitoring in some thermal springs of North India
and Bhutan

"Lucas cell assembly was used to record alpha counts and the radon
concentration is measured by using the calibration constant (10 counts
= 1 Bq/l)."

Table 1. Radon concentration in thermal and natural springs:
"The highest value of radon (441.2 Bq/l) was recorded in a natural
spring at village Swastik Burtu near Gangtok, Sikkim."

How Dangerous is Radon in Buildings? Some Reflections from Europe1
"The water contains 4500 to 12500 Bq/l radon. These. are by far not
the highest concentrations known: in Bad. Brambach in Germany, for
example, 100000 Bq/l"

Therefore, I'll deductively conclude that a sufficient amount of Ra226
does exist, and thereby a subsequent (use-it or lose-it) cache of
LRn222 could be made available for an ion propulsion launch of a
significant spaceship mass, without our having to create one kg worth
of artificial fuel. Of course other forms or raw elements of heavy
ions could be utilized, however greater amounts of applied energy
would be required for utilizing those inactive ions that have no
initial decay velocity to start off with.
. - Brad Guth


BradGuth wrote:
> Using a Th232 breeder reactor of U233, and a good amount of Ra226
> that'll subsequently breed those Rn222 ions, should make those
> continuously available ions of Rn222 rather interesting, as offering
> an extremely fast exit velocity of such hefty radon ions that can be
> focused and/or pumped into a tight beam, much like a laser cannon.
>
> Achieving an ion exit velocity of 0.2'c' or slightly better seems
> doable, even though our firing tubes may seem rather long for our
> interstellar craft that'll demand all the exit velocity that can be
> forced upon those ions. Of course, once getting ourselves past the
> interstellar L1 is when we'd have to start thinking of ion
> retrothrust, unless overshooting the mark isn't worrisome.
> . - Brad Guth