Experimental observation of the dependence of 240 nm central spectral region in the third continuum of argon on pressure

Using high current relativistic electron beam to pump pure argon transverse ly, the dependence of 240 nm central spectral region in the third continuum of argon on pressure is observed, which indicates that 3 X 10(5) Pa is the optimal pressure in producing this central spectral region, and proves tha t this central spectral region arises from the charged clusters.