  The CHIANTI atomic database provides sets of assessed data used for
simulating spectral observations of astrophysical plasmas. This article
describes updates that will be released as version~10.1 of the database. A key
component of CHIANTI is the provision of ionization and recombination rates
that are used to compute the ionization balance of a plasma over a range of
temperatures. Parameters for calculating the ionization rates of all stages of
ions from H through Zn were compiled and inserted into the CHIANTI database in
2009. These were based on all measurements that were available at the time and
supplemented with distorted wave calculations. Since then, there have been a
number of new laboratory measurements for ions that produce spectral lines that
are commonly observed. Parameters have been fit to these new measurements to
provide improved ability to reproduce the ionization cross sections and rate
coefficients, and these are added to the database. CHIANTI 10.1 also includes
new recombination rates for the phosphorus isoelectronic sequence, and the
updated ionization and recombination rates have been used to calculate a new
ionization equilibrium file. In addition, CHIANTI 10.1 has new electron
collision and radiative datasets for eight ions in the nitrogen and oxygen
isoelectronic sequences, and updated energy level and wavelength data for seven
other ions.
