An R-matrix with pseudostates approach to the electron-impact excitation of HI for diagnostic applications in fusion plasmas

Electron-impact excitation dross;sections for transitions between terms up to the n = 5 shell of neutral hydrogen have been calculated using the R-matrix method with pseudostates and compared with previous studies. Maxwell-averaged effective collision strengths have been prepared and used in population calculations to examine effective emission coefficients for diagnostic applications in fusion plasmas. Our results remove an uncertainty in the reaction rates of an important class of atomic processes governing H I emission in plasmas.