A set of novel instruments has been developed to measure the volatile component of solid particles emitted from the surface of an isolated ice/dust mixture (''sample''). To detect such particles a pressure gauge is mounted inside a volume which has a narrow tube placed on top for particles to enter. The experiments are positioned about 0.5 m away from and below the sample. Particles, after falling through the tube are collected in a heated cup, ices evaporate and produce a gas pulse inside the volume. The pressure, registered by the gauge, will decrease with a time constant of about 0.4 s. In some instruments the single cup is replaced by a multiple cup collector. In recent comet simulation experiments (KOSI 5 and KOSI 6) with ice/dust mixtures over 1200 gas pulses were observed. They fall into two categories: (a) short pressure pulses with a fast rising amplitude followed by the expected exponential decay, and (b) long pulses with rise times of about one second and several tens of seconds decay times. The former pulses are associated with ice particles, whereas the latter pulses are attributed to skeleton silicate grain agglomerates which have ice imbedded in them. The estimated mass distribution ranges from 2¿10-10 g to 10-5 g of volatile material.

Ice particles are emitted at maximum rate immediately at turn-on of the the artificial sun and drop to much lower frequencies within less than one hour. ''Mineral'' particles, in contrast, reach their maximum frequency later, with their abundance also decreasing but less pronounced. Since gas emission varies very little while the ice particle frequency drops rapidly, it appears that the particle rate is not controlled by the gas flux's drag force, but by the availability of particles suited for acceleration at the surface of the sample. ¿American Geophysical Union 1991