collimation and subsequent con®nement of the dust plume can be explained with simple models of the wind±wind interaction 2 , or whether more detailed three-dimensional calculations are required, such as those of Walder 20 . Spectral studies of the plume should reveal the thermal and chemical evolution of the dust as it is swept outwards into the interstellar medium, and should also yield information on processes underlying the binary-mediated dust-creation mechanism. With a few dusty WR systems open to study with this method for the detection of binary stars, wider questions of dust formation in this class of objects can now be addressed. M

Recent experiments on the interaction of intense, ultrafast laser pulses with large van der Waals bonded clusters have shown that these clusters can explode with substantial kinetic energy. By driving explosions in deuterium clusters with a 35 fs laser pulse, we have accelerated ions to sufficient kinetic energy to produce DD nuclear fusion. By diagnosing the fusion yield through measurements of 2.45 MeV fusion neutrons, we have found that the fusion yield from these exploding clusters varies strongly with the cluster size, consistent with acceleration of deuterons via Coulomb explosion forces.

Exploiting the energetic interaction of intense femtosecond laser pulses with deuterium clusters, it is possible to create conditions in which nuclear fusion results from explosions of these clusters. We have conducted high-resolution neutron time-of-flight spectroscopy on these plasmas and show that they yield fast bursts of nearly monochromatic fusion neutrons with temporal duration as short as a few hundred picoseconds. Such a short, nearly pointlike source now opens up the unique possibility of using these bright neutron pulses, either as a pump or a probe, to conduct ultrafast studies with neutrons.

We present the first in-target measurements of the electrons produced by an ultraintense ͑I . 10 19 W͞cm 2 ͒ laser pulse incident on a massive solid target. Total conversion efficiency, mean electron energy, and electron cone-angle measurements are presented. A relationship between the target material and the mean electron energy is also discussed. [S0031-9007(98)06709-X]