Kinetic temperature gradient driven modes in inhomogeneous plasmas

New unstable temperature gradient driven modes in an inhomogeneous plasma are identified. These modes represent transient $\omega \simeq k_{\Vert }v_{th}^{(e,i)}$ sound oscillations in magnetized plasma that are kinetically destabilized via Landau interactions. Electron and ion sound branches are unstable for large values of the Larmor radius parameter $$ respectively. The instability occurs due to a specific plasma response that significantly deviates from Boltzmann distribution in the region $k_{\bot}\rho_{i,e}\gg 1$ . Pacs: 52.35 Kt, 52.35 Qz