Open AccessCaesium Balance of the ISIS H Penning Ion Source
Author(s) -
O. Tarvainen,
Dan Faircloth,
Scott Lawrie,
Tiago Sarmento,
Robert Abel,
John Macgregor,
C. Cahill,
T Stanley,
Mark Whitehead,
T. Wood
Publication year - 2022
Publication title -
journal of physics. conference series
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.21
H-Index - 85
eISSN - 1742-6596
pISSN - 1742-6588
DOI - 10.1088/1742-6596/2244/1/012031
Subject(s) - caesium , cathode , work function , atomic physics , ion , ionization , ion source , beam (structure) , range (aeronautics) , hot cathode , chemistry , materials science , electrode , physics , optics , inorganic chemistry , organic chemistry , composite material
We have developed a model predicting the equilibrium caesium coverage work function of the cathode (in eV) and the expected H - beam current (in arb. units) of the ISIS Penning ion source. The model is based on semi-empirical expressions for the cathode work function, negative ion surface ionization yield, and caesium adsorption and desorption rates. We compare the model predictions to experimental data with 760 μs discharge and 250 μs beam pulses. It is concluded that the ISIS Penning ion source operates near the optimum cathode work function in a wide range of caesium pressures and cathode temperatures. The model implies that long pulse operation of the source requires elevated Cs oven temperature and improved cathode cooling.