The density and pressure of helium in bubbles in implanted metals: A critical review

A review is presented of experiments and calculations which have yielded information on the state of helium in small bubbles in implanted metals. Recent findings which indicate extremely high densities and pressures are discussed in the light of the mechanical properties of the metal substrate. A short review of research on high pressure helium is also presented in order to establish an equation of state relevant to small room temperature helium bubbles.