NetNews Usenet Archive 1993 #1/NN_1993_1.iso/spool/sci/physics/fusion/3154

Text File | 1993-01-05 | 5.5 KB | 118 lines

Newsgroups: sci.physics.fusion
Path: sparky!uunet!munnari.oz.au!spool.mu.edu!caen!uvaarpa!murdoch!kelvin.seas.Virginia.EDU!crb7q
From: [e-mail] (Cameron Randale Bass)
Subject: Re: Wegde-Out; liquid lithium; UC & Pd; liquids with wide temp ranges
Message-ID: <[e-mail]>
Sender: [e-mail]
Organization: University of Virginia
References: <[e-mail]>
Date: Tue, 5 Jan 1993 18:01:15 GMT
Lines: 106

In article <[e-mail]> [e-mail] writes:
>
>Hi folks,
>
>A few quick comments:
>
>
>1. WEDGE-OUT
>
>My favorite response so far was from Dieter:  He described my "wedge-out"
>mechanism as sounding a lot like wishful thinking.
>
>Alright!  That's exactly the kind of whack-em-about-the-ears criticism
>that the UC (ultracavitation) idea needs.  Dieter zeroed in on exactly
>the weakest link:  Can you _really_ get massive acceleration through this
>kind of proposed mechanism, or not?
>
>So I'll echo the challenge:  Can anyone out there show one way or the
>other whether this wedge-out idea is either bogus or has merit?

     A couple of quick points:

     1) in stable cavitation in acoustical fields,
     the sonoluminescence occurs shortly after the bubble reaches maximum
     radius (i.e. just as the bubble starts its inward cycle.  Keep in
     mind that in stable sonoluminescence, the bubble itself does not
     completely collapse.).  This implies that the sonoluminescence
     is mediated by a strong shock in the vapor itself (See Barber
     and Putterman PRL: 69:3839 (1992) among others),

     2) it is not clear what physical/thermodynamic meaning 100,000 K has for
     this process (a discussion of 'huge' fugacity should be kept in mind
     here).  However, all of the component species should be fairly well
     ionized at that point if it has any physical meaning.  Putting aside
     the thought that it probably has limited physical meaning, at that point
     there are very good electrostatic reasons for the character
     of the interaction to change somewhat drastically.
     I would also point out that the concept of ordinary fluid dynamic surface
     tension breaks down well before that point (to put it mildly).

     3) If you seriously want to present a model, the burden of proof is
     on you to describe such things as
          a) why your process does not violate the second law,
          b) why surface tension itself does not seem to operate in
             the 'wedgeout process',
          c) why diffusion and damping do not significantly operate,
          d) how one applies a fluid continuum approach to a putatively
             ionized gas,
          e) how one can get a further 11 order of magnitude concentration
             of energy beyond the concentration probably caused by an
             ionizing shock, especially considering that at indicated
             spectral temperature, electromagnetic interactions will
             dominate long before fusion energies are reached,
          f) why it seems to be somewhat at variance with current
             indications of the mechanism of stable sonoluminescence.

     Among other side issues, quantification also seems to be a
     fairly significant burden.

>Also, is there any chance someone out there can simulate this issue?
>(I tend to be leary of easy proofs for a system that is so drastically out
>of equilibrium.)

     Sure, for $50,000 + overhead, I'd be glad to.  Sonoluminescence
     is not a trivial problem, but there are certain obvious ways of
     approach at this juncture.

     The problem is getting someone to pay for the work since I value my
     lunch money.  However, I think the application to fusion to be probably
     somewhat limited.

>Again, the key premise is that a very sharp pressure/vacuum transition on
>an inwardly collapsing void will lead to substantial increases in inward
>velocity for some fraction of the surface molecules.  True or false?  Why?

     More like 'substantial increases in local KE for some fraction of
     the interior molecules'.  However, the mechanism is likely
     somewhat different than you propose, in that it may be the shedding of
     a strong shock into the vapor bubble.  If so, it appears to be of
     limited value in fusion studies unless you can explain why a partially
     ionized gas can further concentrate energy.  Our good friends in the
     hot fusion business can probably explain better than I how difficult
     that is.

>4.  LIQUIDS WITH WIDE TEMPERATURE RANGES
>
>It's implicit in the UC draft, but let me state it in a single sentence:
>
>Liquids that remain liquid over a very wide range of temperatures are
>much more likely to be interesting than ones that have only a short range
>between solidification and vaporization.
>
>Thus liquid helium would be a _really_ poor UC choice by these criteria,
>and liquid mercury would be a quite good one.  Mixtures of liquids will
>general do better by this criterion than single-composition liquids

      So something that is doubly ionized is harder to get close together
      than something that is 80x ionized?  Keep in mind, at hot fusion
      energies your original fluid is gone.  All that remains is that nucleus
      and all its charges.

                                dale bass
--
C. R. Bass                                          [e-mail]
Department of Wildebeest
Transvaal                                           [phone]