Heavy-ion-induced hydrodynamic motion in lead targets

The hydrodynamic response of metal targets to volume heating by energy depo sition of intense heavy-ion beams was investigated experimentally. Recent i mprovements in beam parameters led to a marked increase in specific deposit ion power: 2 (.) 10(10) Ar-40(18+) ions of 300 MeV/u focused to a spot size of 300 mum (sigma) x 540 mum (sigma) yield a specific deposition energy in solid lead of approximately 1 kJ/g in the Bragg peak, delivered within 250 ns [full width at half maximum (FWHM)]. This value allowed us for the firs t time to observe heavy-ion-beam-induced hydrodynamic expansion of metal vo lume targets. Measurements comprise expansion velocities of free surfaces o f up to 290 +/- 20 m/s, surface temperatures of ejected target matter of 16 00-1750 K, and pressure waves in solid metal bulk targets of 0.16 GPa maxim um absolute value and 0.8 mus FWHM. The experimental results agree well wit h the results of a 2D hydrodynamic code. Inside the interaction zone, which can only be accessed by simulation, maximum temperatures are 2800 K and ma ximum pressures are 3.8 GPa.