Optical investigations in the megabar range using a chamber consisting of a rounded cone and a flat foundation

The possibility of creating chambers for the megabar pressure range using a rounded cone-flat plane geometry in which, in spite of the small size of the high-pressure region, it would be possible to perform optical measurements and determine the pressure using the R luminescence line shift in ruby under pressure is experimentally investigated. The luminescence spectra of ruby grains placed in different parts of two chambers were measured in order to study the pressure distribution. The cone and plane chamber elements were made of transparent diamond and of carbonado. The pressure distribution with different applied loads was determined, and the measured pressure distributions are shown. The highest attained pressure was 0.7 Mbar. The measured pressure distribution differs from the one following from Hertz's equation. The facts supporting the notion that the chamber constitutes a quasi-hydrostatic pressure chamber are noted.