The graphite dome of the SunCell would not survive long at the operating temperatures claimed, 426-1426 C. From POCO, a leading producer of graphite:
Temperature Effects
The differences in oxidation behavior of the various grades of graphite are widest at the lowest tempera- tures, tending to disappear as the temperature increases. The “oxidation threshold temperature,” defined as that at which a sample loses approximately one percent of its weight in 24 hours, is about 570°C for purified graphite, while nonpurified graphite is about 430°C (Figure 18-1).
The oxidation of graphite is highly temperature- dependent. At temperatures up to about 350°C, no detectable oxidation occurs. As the temperature is increased, the rate of reaction increases rapidly, according to the Arrhenius equation.
http://poco.com/Portals/0/Literature/Semiconductor/IND-109441-0115.pdf
Note also the oxidation rate vs temperature for purified graphite in the top right graph on the following page. The data here are for pyrolytic rather than natural graphites. In testing, the % weight loss is highly dependent on surface/volume ratio of the sample but there's no way the dome has a useful lifetime at 1426 C. I expect Mills and his fans could offer any of a dozen ad hoc reasons why this isn't a problem.
That's good to know, but there is no graphite dome mentioned in the fourth quarter report afaik.
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