60. 



were increased to 8 inches deep and 24 inches in diameter, this ratio 

 is slightly above .4, and the calculated input is slightly above .01 

 watts per c .c . 



DR. KOHMAN: Is this the power necessary to get 900 degrees? 



MR. STRUXNESS: This is the power required to fuse this clay 

 mass . 



MR. MORTON: You will get 900 degrees if you have enough in- 

 sulation at the boundary. 



MR. STRUXNESS. However, Dr. Johnson, who did these ex- 

 periments, feels that these power requirements are conservative. 

 He says that with reasonable insulation in the ground, and with a pit 

 about 20 feet deep and 20 feet in diameter, one might be able to fuse 

 this clay flux material. 



DR. HUBBERT: Wouldn't it be more important if you stated 

 how much energy was required to reach that level? 



DR. CULLER: It would have to be energy-time, wouldn't it, to 

 reduce that temperature? 



DR. HUBBERT: In order to produce fusion the temperature 

 must be raised the required amount. This, in turn, involves the ad- 

 dition of an amount of heat equal to the heat capacity of the material 

 at the melting temperature with respect to that of the initial tempera- 

 ture, and then an additional amount of heat to product fusion. The 

 power required, it seems to me, is fundamentally ambiguous because 

 the heat produced by any given power is proportional to the time. 

 Since there are heat losses by conduction, these can be kept small 

 only by keeping the time as short as possible, which implies rapid 

 heating at a high power level. The object, therefore, should be not 

 to find the least power that would permit fusing temperature to be 

 reached, but rather to produce fusion at the least energy cost. At low 

 power levels the energy expenditure could be without limit because of 

 heat leakage; at high power levels the energy required would approach 

 that for fusion without leakage. 



MR. STRUXNESS: Further work is needed to extend the points 

 on the curve, and I will certainly talk to him about it. 



