  The enhancement of a cryogenic radio frequency 22 pole trap instrument by the
addition of ring electrodes is presented in detail. The ring electrodes tightly
surround the poles and only a fraction of the applied electric potential
penetrates to the trap axis, facilitating the fine control of slow cold ions. A
precise computational model, describing the effective mechanical potential
created by the applied static and rf fields, governing the ion behaviour, is
employed to demonstrate and understand the operation of our setup. The use of
ring electrodes for improved extraction of cold stored ions is shown. Variable
trapping potentials, placed on one ring electrode, can be used to control the
evaporation of only those $\text{H}^+$ ions from the trap, whose kinetic energy
exceeds the barrier. This ring electrode trapping opens new possibilities to
study processes of minimal kinetic energy release, e. g. spin exchange. We
propose a robust modified method for the determination of temperature dependent
ion molecule reaction rates, resistant to effects caused by neutral gas
freezing and demonstrate it on the reaction of $\text{CO}^+$/$\text{CO}_2^+$
with $\text{H}_2$/$\text{D}_2$. Finally, the use of a supercontinuum laser for
quick localisation of spectroscopic bands is examined on the $\text{N}_2^+$
Meinel system.
