A particle characterization in a jet of particles in vacuo.

The invention relates to a device (100) for characterizing particles moving under vacuum in a jet of particles, characterized in that it comprises: - a system (110) for generating a jet of particles in a chamber (120) which is associated with a pumping means (121) of the fluid present in the chamber in order to conquer a vacuum in this chamber; - a laser (30) emitting a laser beam in the form of pulses whose characteristics are controlled by a control means (27) laser with an associated optical device (60) arranged to focus said beam in the chamber (120 ) perpendicular to the propagation direction of the jet particles to create, in a focal volume (50) having at most one particle of the jet, a plasma by the interaction between the laser beam and the particle jet, said plasma emitting d other particles, characteristics of the interaction between the laser and the particles of the jet; - at least one detection device (61, 62) arranged to detect particles emitted by the plasma and which is associated a means for acquiring and processing data (28) from the detection of the particles emitted by the plasma.