Cavitation ( gamma ray production verified )

[Siuboy]

I have previously suggested the deliberate use of non inertial cavitation in a plasma, pulsing the “bubble” with short bursts of highly intense lasers ( instead of acoustic fields ). I thought that the resulting collapse of the “bubble” would probably produce high energy gamma rays. I read today that this has been accomplished at the University of Strathclyde…
The experiments were carried out on the Gemini laser in the Central Laser Facility at the Science and Technology Facilities Council’s Rutherford Appleton Laboratory.
The gamma rays produced were termed “the brightest gamma rays on earth”
Here is the URL for the article : http://www.sciencedaily.com/releases/2011/09/110919113836.htm

[Rezwan]

Thanks for the info! You should also add a link to your previous suggestions and implications.

From the article, I like:

The source could also be useful in monitoring the integrity of stored nuclear waste.

It’s not a nuclear waste problems, it’s an integrity problem.

[Siuboy]

I have previously posted to this forum…some time ago ( years)… I also posted to University of Texas to their research program with the US Navy on designing new high speed propellers ( which are particularly vunerable to damage from cavitations ) I think I also posted to a site investigating the possibility that it was cavitation that was causing some of the release of excess heat in Cold Fusion experiments and release of particles synonymous with “fusion”… No body was interested, probably due to negative effects of claimed “over unity” from cavatation water heaters.

[jamesr]

As I posted on FB

Apart from failing to mention the photon energy range in the article. It makes an obvious error quoting
“The peak brilliance of the gamma rays was measured to be greater than 1023 photons per second, per square milliradian, per square millimetre, per 0.1% bandwidth.”
Whereas the Nature paper abstract actually says
“10^8 gamma-ray photons, with spectra peaking between 20 and 150keV, and a peak brilliance >10^23photons s^−1mrad^−2mm^−2 per 0.1% bandwidth, are measured for 700MeV beams, with 10^7 photons emitted between 1 and 7MeV”
Only 20 orders of magnitude out!

It should have been obvious to any science journalist that 1023 photons per second is not very intense, and maybe it should be written with a superscript, or if they can’t then at least as 10^23 or 1e23 notation
Is it too much to ask that proof reading should involve checking the numbers as well as spelling grammar and punctuation?

[vansig]

proof reading has become too expensive and been replaced largely by automation

[Siuboy]

Dear Old Timer,
Do you have a subscription to Nature? Have you read the entire article ? I went to Nature and they didn’t mention cavitation in the press release, just
Gamma-rays from harmonically resonant betatron oscillations in a plasma wake.
I am not sure that I completely understand your overall objections to the report in Science Daily, but even if the magnitude of results is less than the reporter
stated, it still appears that gamma rays were produced. There have been multiple studies that standing sound waves in a fluid that produce non inertial cavitation
that upon collapse of the resulting “bubble” produce a very large shock wave and high temperature. This feature has been used to good effect in commercial hot water heaters. My original suggestion was that the concept of cavitation in a plasma being oscillated by ultra short laser bursts might lead to “ignition” . We know that various techniques are getting close as we better understand the nature of plasma. I know of a professor who has taken ultra slow photographs of what happens ( think pico seconds ) when the “bubble” collapses and he suggests that the phenomena is chaotic and erratic which is to be expected. It suggests that replication of effects will necessarily be affected. Until we better understand the parameters, the effect alone will not be worthwhile. But I think producing gamma rays with a hand held device is an achievement…

[jamesr]

Yes I do has access via my institution.

This has nothing to do with cavitation, acoustic, shocks etc. pressure & temperature are meaningless on this energy/time-scale.
The plasma ‘wake’ is the interaction with the huge EM fields of the laser pulse – not a fluid-like response, you have to think in terms of kinetics of individual ions/electrons.

Laser wakefield acceleration is nothing new, see: http://en.wikipedia.org/wiki/Plasma_acceleration
Similarly there have been improvements in Free Electron Lasers in the last 10 years or so.

This experiment was not about the energy of the accelerated electrons, 700MeV in this case, compared to >1GeV in others. Or the intensity (number of photons) of the resulting X-ray beam.
It was that the spectrum of the betatron excited beam of high energy photons peaked around 150keV rather than the ~10keV typical of previous experiments. Thus the X-rays are now in the ‘gamma-ray’ portion of the EM-spectrum rather than the relatively soft X-rays. (NB. traditionally the gamma terminology is reserved for photons emitted by nuclei rather than electrons)

Although it talked about gamma rays the Science Daily write-up failed to mention the key figure of 150keV, and instead went on about the intensity – which it then quoted incorrectly.

High intensity is needed, but it is the combination of high photon energy, and short pulse duration is key for imaging proteins etc. and make this potentially a big step forward in having a lab sized machine rather than the huge synchrotron accelerators.

[Siuboy]

Dear Old Timer,

Thanks for an excellent post. I was reading some other sources and began to suspect that the report in Science Daily was an exaggeration. You have given me some excellent points to research. I just wish I had better mathematical skills ( which I am trying to remedy ) Like you reported, the extent of the reporter’s
error miscommunicates the true results. I suspect that I would like to follow you on FB, as it seems we have similar interest. I happen to be interested in protein folding, and as you stated, this breakthrough will make imaging proteins more feasible for smaller labs. I tend to think that small operations probably engender more innovation, as the researchers must contend with and overcome financial restrictions.

[vansig]

Siuboy wrote: Dear Old Timer,

Siuboy,
why do you keep addressing people by that, instead of their name?

[Brian H]

vansig wrote:

Dear Old Timer,

Siuboy,
why do you keep addressing people by that, instead of their name?
‘Cause he’s a noob, and doesn’t know that “Old Timer”, “Newbie”, etc. are membership titles based on total postings.

[Siuboy]

Thanks. I figured that out, once I got the input. Did you see that Kimberly Clark ( who took out patents on “Bubble Fusion” ) has decided to fund research into this area ( production of gamma rays ). They already use cavitation to aid their manufacturing processes and may have some ideas of how to use this new variation to
good advantage.

[Author]

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