Abstract The work reported in this paper addresses two aspects. In the first part, numerical simulations are conducted to examine
the impact of magnetic equilibrium shaping (elongation and triangularity), on both conventional Ion Temperature Gradient
(ITG) modes and Short Wavelength Ion Temperature Gradient (SWITG) modes. This analysis is performed considering the
experimental profiles and parameters of the ADITYA-U tokamak, employing the nonlinear global gyrokinetic Particle-in-Cell
(PIC) code ORB5. The linear and nonlinear collisionless electrostatic simulation of these modes are carried out with kinetic
ions and adiabatic electrons. From the linear results, it has been observed that the magnetic equilibrium shaping slighty reduced
the growth rates and widened the spectrum, and the maxima of growth rate curve is shifted to higher toroidal wave number.
We find that the heat flux is reduced by a significant ≃ 35% for the true circular MHD magnetic equilibrium as compared
to ad hoc concentric circular equilibrium reported in [1]. A further ≃ 10% reduction in the heat flux is seen with magnetic equilibrium
shaping. In the second part, linear collisionless electrostatic simulation studies of ITG coupled with fully kinetic electrons
(both trapped and passing electrons are treated kinetically) using a drift-kinetic ordering is performed. It can be seen from
the linear results that, in presence of kinetic electrons, the growth rate and real frequency of the ITG mode are increased
significantly for ADITYA-U parameters and a mode propagating in the electron diamagnetic direction is identified at high
toroidal wavenumbers.