Drift wave analysis including density temperature gradients of plasma near the plasma-pause is considered. The presence of ''hot'' plasma (T>10 eV) outside the plasmasphere requires consideration of drift instability condition that the ratio &eegr;=∂lnT/∂lnn remain within certain values. Calculations using possible plasma parameters at the plasma pause show that appropriate values of &eegr; exists for the possibility of the drift instability and waves &ohgr;~10-2 rad sec-1 in Pc 3 and Pc 4 range of micropulsations can be internally generated by the plasma inhomogenieties.