  The HARP experiment was designed to study hadron production in proton-
nucleus collisions in the energy range of 1.5 GeV/c-15 GeV/c. The experiment
was made of two spectrometers, a forward dipole spectrometer and a large-angle
solenoid spectrometer. In the large-angle spectrometer the main tracking and
particle identification is performed by a cylindrical Time Projection Chamber
(TPC) which suffered a number of shortcomings later addressed in the analysis.
In this paper we discuss the effects of time-dependent (dynamic) distortions of
the position measurements in the TPC which are due to a build-up of ion charges
in the chamber during the accelerator spill. These phenomena have been studied
both theoretically and experimentally, and a correction procedure has been
developed. First, the dynamics of the positive ion cloud and of the full
electrostatics of the field-cage system have been modelled with a
phenomenological approach and a general correction procedure has been developed
and applied to all data settings. Then, the correction procedure has been
benchmarked experimentally by means of recoil protons in elastic scattering
reactions, where the track coordinates are precisely predictable from simple
kinematical considerations. After application of the corrections for dynamic
distortions the corrected data have a performance equal to data where the
dynamic distortions are absent. We describe the theoretical model, the
comparison with the measurements, the distortion correction method and the
results obtained with experimental data.
