Direct Method of Calculating the Grüneisen Parameter γ Based on Shock-Wave Measurements of Metals

On the basis of the well‐established relationship $\mathrm{U\hspace{0.17em}=\hspace{0.17em}A\hspace{0.17em}+\hspace{0.17em}Bu}$ ($U$ denoting shock velocity, $u$ particle velocity, and $\mathrm{A,\; B}$ experimental constants), it is shown that the following explicit formula can be used for the evaluation of the Grüneisen parameter: $$\text{γ\hspace{0.17em}=\hspace{0.17em}{U(2U\hspace{0.17em}−\hspace{0.17em}A)[A\hspace{0.17em}+\hspace{0.17em}(B\hspace{0.17em}−\hspace{0.17em}1)U]\hspace{0.17em}−\hspace{0.17em}(}\frac{1}{3}{\mathrm{AU)(U\hspace{0.17em}-\hspace{0.17em}A)\hspace{0.17em}-\hspace{0.17em}BA}}^3\mathrm{\}\hspace{0.17em}/\hspace{0.17em}U(U\hspace{0.17em}-\hspace{0.17em}A)(U\hspace{0.17em}+\hspace{0.17em}A).}$$ This is a short cut of its kind. Although its resultant values of $\gamma$ reflect some differences similar to those between the Slater and Dugdale–MacDonald schools, the present method of computation can lead to a satisfactory evaluation of the equation‐of‐state data. In addition, direct calculation of sound velocity behind the shock front turns out to exhibit an interconnection between static and dynamic compressibilities. Such a link should be of value for pursuit to gain basic understanding of high pressures.