January 10, 1995
Dr. Seth Putterman
UCLA Physics Dept.
405 Hilgard Avenue
LA, CA 90024
Dear Seth -
I just wanted to take a few moments to checkpoint our conversation.
1) it is raining cats and dogs in LA.
2) At 70 kHz dilute isopropanol crazes Lucite/Plexiglas tubes, emitting
a distinctly non -OH odor. Time constant on the order of a couple of minutes.
Water did not damage the apparatus, nor did isopropanol allowed to stand
in the tubes for long periods unexcited.
Apparatus:
Acoustic lens cemented to conventional BZT transducer. The lens was parabolic
(was intended) to focus at the air water interface.
Approaching the atomization frequency from below produced a peculiar static
hump in the meniscus just prior to nebulization (fizzing). My transducer
was on the bottom of the cylinder, isolated from the tube walls with 2"
grommet. My amp was a push-pull twin tube audio amp with two air-core
toroidal transformers replacing the standard output transformer so that
it would pass the high frequency. Iron core transformers poop out around
25 kHz due to saturation losses.
3) I proposed some experiments:
a) try sonoluminescence with salts of Li 6 of Li 7.
(the natural abundance is 7.42 and 92.58% respectively)
b) vary pH, frequency and temperature. (safety first)
c) try sonoluminescence with D2O and T2O.
d) try sonoluminescence with Li 6 of Li 7 in D2O and T2O.
4) You replied:
a) that the current setup and phenom lend would be better facilitated if
the Lithium was in gaseous form to make the bubble.
b) that sodium doesn't emit its yellow line when introduced.
c) that protons (from HCL) don't change the phenom.
d) That T2O is very toxic and that T has low activation energy to comb with
D.
e) You suggested two items of legwork, 1) look at Li barrier energy, and
2) resurrecting my old apparatus.
I appreciate your input.
In closing I would like to make a couple far out suggestions that might
be easy to implement.
1) tapered velocity amplifier, This can be metal bar stock that is turned
from one diameter at the crystal, to another diameter at the fluid interface.
(If you taper the container the liquid will do it for you.) The payoff is
that the amplitude varies inversely with the cross section, so you can get
a bit of a singularity going. I like free singularities.
2) strange fluids. Mercury is a penny a gram in bulk from Aesar. Tapered
Mercury column makes an interesting device. It would trap light, and alpha
particles though. Molten lithium would have to be isolated from the transducer
by a velocity amp so that it didn't "Curie-out" the BZT.
I'd be happy to contribute further. My specialty is computer simulation.
I would like to fire up my old apparatus, but it would take a few bucks
let me say.
Anyway, pour a cup of coffee, take refuge from that rain.
Your friend,
Van Warren
M.S. CS M.S. AAE
501-224-7434 voice/fax
P.S. I spoke briefly with Kenneth Suslick (217-333-2794, 2685 fax) at the
U of I Urbana. He said they had observed this Plexiglas breakdown phenomena
as well. He attributed to local heating of the Plexiglas. For some reason
the isopropanol cavitation characteristics were different enough than water
so that a fair amount of sound energy ended up in the plastic. The odor
that I observed was probably that of melting plastic. Interesting. In regards
to the nuclear suggestions Kenneth referred me to Willie Moss (510-422-7302)
at Lawrence Livermore. He mentioned that they were looking for neutrons
in sonic environments.
P.P.S. I spoke with Willie Moss, yet another interesting and engaging fellow
in this -what I am coming to understand- well established field. What is
wonderful about it is what we have yet to find out. Willie Moss has a lot
to say about this in the D2O area. He has done extensive calculations as
well as a series of interesting experiments in this area. He was quite interested
in the Hg column idea, because it offers the op to increase bubble size
and therefore shock intensity. He observed that the limitation of light
and other particle emissions being trapped would not apply to neutrons,
and that neutron emission would definitely portend more interesting things.
He underscored as the recent article does that a) rather few materials sonoluminesce
and b) the phenom is somewhat brittle with respect to frequency and other
parameters.
This has been a great technical adventure for me. Hopefully in some small
way these three discussions will yield some more insight for us all.
Van Warren
M.S. CS M.S. AAE
501-224-7434 voice/fax