Thirty years ago, one of us (E.M.G.) theoretically justified the possibility of synthesizing diamonds in a cavitating fast fluid flow [1]. In that and more recent works [2, 3], variants of the cavitation synthesis of diamonds in nature were discussed. The essence of the idea is as follows. When a fluid rises rapidly from the mantle to the ground through a narrow channel–crack formed by it, sharp pressure differences arise. According to the Bernoulli equation, pressure in the fluid flow is inversely proportional to the velocity squared. Therefore, pressure decreases in a narrow spot, which givesrise to the appearance of gas bubbles. When the fluid again enters a wide place, pressure is recovered and bubbles collapse. Calculation shows that pressure can increase by several orders of magnitude. As was calculated in [1], pressure induced when bubbles filled with a carbon-containing gas collapse is sufficient for diamond synthesis. In [1, 2], it was assumed that the fluid contained CO_2, but a more recent analysis of diffusion velocities from the collapse medium showed that only hydrogen has a sufficiently high diffusion velocity. Therefore, a hydrocarbon substrate such as methane must be the initial substance.
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