e noted, is not actually a description of what the electronsmay be doing as much as a prescription for the calculationof appropriate averages approximating the bulk propertiesof electrons in this state. It leads <strong>to</strong> an equation for thepressure that satisfies the condition for isentropiccompression: ,P = KN 5 " 3 V 5 - 3 + nV25 [(kT) 2 / K 2 (N/V)
sion schemes by noting, as pointed out above, that a Fermidegenerate state will support isentropic compression fromany strength shock wave because of the structure of itsequation of state. Such compression exists; the questionis how <strong>to</strong> obtain it both before <strong>and</strong> after Fermi condensation.Third, the crux of the argument, then, is that we knowthe equation of state well enough <strong>to</strong> rule out the exoticstates described above. This may perhaps be the case forthe pellets now in use <strong>and</strong> for future target designs. Butthis fact is more a statement of the experimental philosophyof the program than a statement about physicalpossibility. The current research program depends veryheavily on an interaction between a set of computercodes, most notably LASNEX, that are used <strong>to</strong> interpretexperimental results <strong>and</strong> the experiments themselves.LASNEX is not a theoretical description of the laser fusionprocess as much as it is a phenomenological collection ofprevious experimental results. The next experiment is thusalways constrained <strong>to</strong> reproduce previous results <strong>and</strong> socannot, in this conservative environment, ever produceanything qualitatively new. When anomalous results areseen experimentally, results that do not conform <strong>to</strong> theCourtesy of Or. Wins<strong>to</strong>n BoalickA stably self-organized magnetic structure in a plasma. <strong>Fusion</strong> scientist Dr.Wins<strong>to</strong>n Bostick, who has described the physics of these self-generating, magnetic filaments in a fusion plasma, has proposed a "hybrid" approach <strong>to</strong>fusion combining magnetic <strong>and</strong> inertial techniques. This approach has alsobeen proposed by Dr. Friedwardt Winterberg.predictions of the computer code, they are downplayed.If they do not offer the immediate possibility of more'efficient compression, they are ignored.Similarly, experiments are designed, of necessity, withinthe bounds of the existing computer codes. New interactionsthat are not in the computer codes will be excludedfrom the considerations affecting new target designs.Thus, experimental progress becomes a self-fulfillingprophecy <strong>to</strong> a large extent. A small, well-delineated areaof possible parameter space gets very thoroughly mappedout <strong>and</strong> pellet design, driver, <strong>and</strong> geometry get optimizedwithin this goldfish bowl; this is a local optimization thathas little sense of the global configuration. Might therenot exist new regimes that differ in some parameter by anorder of magnitude from the current experiments (likemagnetic field) <strong>and</strong> that would <strong>to</strong>tally change the physicsof compression <strong>and</strong> absorption? 20 In principle, such regimescannot be ruled out, but the current researchstrategy will not find them. Of course, the equation ofstate for the current regimes is reasonably well known,but what does this say about other possibilities?Fourth, the Fermi equation of state certainly seems <strong>to</strong>be an exception <strong>to</strong> what we have just said. Here is anequation of state that is well known<strong>and</strong> well tested. We can reply onlythat such confidence perhaps is agood hypothesis but is not sufficient<strong>to</strong> rule out other possibilities. Ourignorance of the actual dynamics ofthe electron itself, which can be describedby no existing theory, or highdensitycollections of electrons, is afact. Perhaps high magnetic fieldschange the statistical considerationson which the Fermi equation of stateis based. Perhaps the rapidly changingtemperatures <strong>and</strong> pressures result inthe Fermi equation of state (an equilibriumlaw) being overwhelmed byother phenomena. Perhaps, more important,the equilibrium predictionsof the equation are relevant on differentlength scales, whereas the energeticsof the fusion pellet are determinedby localized energy considerationsof soli<strong>to</strong>ns, filaments, or thelike. All these possibilities are at leastas plausible as the current assumptionthat the equilibrium statistical mechanicsof a Fermi gas apply <strong>to</strong> theelectrons in a fusion target.Fifth, the final objection <strong>to</strong> our proposalis that even if isentropiccompression <strong>and</strong> new states of matterexist, they are not fundamentally differentfrom the normal ones; that is,they contain energy in the same way<strong>and</strong> result in the same final compression<strong>and</strong> heating. This argumentOc<strong>to</strong>ber-November 1981 FUSION 31
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