Beam sources hyperthermal

Fig. 6. Schematic diagram of the laser-detonation hyperthermal beam source, the dififerentially pumped scattering region containing the target surface, and the rotatable mass spectrometer detector.

Fig. 7. Schematic diagram of the interaction region, showing the orientation of the effusive plasma and hyperthermal beam sources, chopper wheel, target surface, and detector.

The development of hyperthermal neutral beam sources, some eight years ago, has disclosed a new field of beam research on charge transfer processes between neutral particles in their electronic ground state. In particular, charge transfer with low endoergicity of the order of 1 eV turned out to be very efficient and therefore has been studied extensively between its threshold and, say, 50 eV. The special interest of this field lies in its close relationship with chemical reaction kinetics and, from a theoretical point of view, its suitability to tell us more about diabatic behaviour at the crossing of potential energy surfaces. 

This conclusion was tested with a practical experiment in which the erosion yield of polystyrene under exposure to the effusive plasma source was measured with and without the addition of the pulsed hyperthermal Ar beam. In this experiment, the Ar beam pulse was not chopped, so the entire beam pulse produced from the laser detonation source was allowed to strike the surface. The erosion yield was determined by placing a screen over the samples during exposure and measuring the etch depth... 

---