Metallization of fluid hydrogen by multiple shock compression

The electrical conductivity of fluid, molecular hydrogen is studied to a de nsity of 0.38 mol cm(-3), which is about a tenfold compression from the ini tial, ambient-pressure, liquid hydrogen state. The hydrogen was compressed by means of a reverberating shock wave. By compressing the hydrogen with a rapid series of relatively weak shock waves instead of a single strong shoc k wave, we minimize the heating of the sample and achieve very high densiti es. Calculated densities were in the range 0.29-0.38 mol cm(-3), and calcul ated temperatures were in the range 1600-3100 K. The data indicate that hyd rogen undergoes a continuous transition from a fluid, molecular semiconduct or to a fluid, molecular metal at a pressure of 1.4 Mbars and a calculated temperature of 2600 K.