The Scandinavian Nielsen Source

Thus surface ionization is a superior method for a restricted number of elements. 3.2.4 The Scandinavian (Nielsen) Source 

A number of sources are modifications or further developments of the Scandinavian-type source  

The hollow cathode source in which the plasma is contained inside the cathode (advantage very high temperature). 

The source developed by Kirchner being much smaller than the Nielsen source and containing an intermediate grid, a modification which causes very low contamination from neighbouring masses. 

The Harwell source having a rectangular extraction geometry and an axial arrangement of the filament near the outlet slit. 

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