Investigation of atomic and molecular clustering in a pulsed gas-dynamic jet with a pyroelectric detector

The clustering of atoms and molecules in a pulsed gas-dynamic jet has been investigated by the method of time-of-flight measurements performed with an uncooled pyroelectric detector (PED). The method is based on measuring the amplitude of the pyroelectric signal induced on the detector by a molecular (atomic) beam and the particle velocity in the beam as a function of the gas pressure above the nozzle. In addition, the number of molecules (atoms) emerging from the nozzle in a pulse has been measured. We describe the method and present the results of our studies on the clustering of He, Xe, CH(4), CO(2), and other gases. The peculiarities of the detection of molecular and cluster beams with PED are considered. We show that the described method allows the clustering threshold as a function of the gas pressure above the nozzle to be determined. We have established the threshold pressures at which particle clustering in the jet begins. Optimal conditions for the generation of intense cluster beams have been found.