Evolution of the electrostatic energy of the x field component U_Ex scaled to the initial kinetic energy E_k0. Panel a: evolution of U_Ex/E_k0, where E_k0 is the total initial kinetic energy for different values of the ratio between plasma and cyclotron frequency ω_p/ω_c. Panel b: evolution of U_Ex/E_k0 in relation to the increasing value of the characteristic thermal velocity of the hot plasma component v_th. Panel c: evolution of U_Ex/E_k0 in relation to the increasing value of the ratio between the hot and background plasma density n_th/n_tb.