Generalized Langmuir waves in magnetized kinetic plasmas

The properties of unmagnetized Langmuir waves and cold plasma magnetoionic waves (x, o, z and whistler) are well known. However, the connections betwe en these modes in a magnetized kinetic plasma have not been explored in det ail. Here, wave properties are investigated by numerically solving the disp ersion equation derived from the Vlasov equations both with and without a b eam instability present. For omega(p)>Omega(e), it is shown that the genera lized Langmuir mode at oblique propagation angles has magnetic z-mode chara cteristics at low wave numbers and thermal Langmuir mode characteristics at high wave numbers. For omega(p)<Omega(e), it is shown that the (oblique) L angmuir mode instead connects to the whistler mode at low wave numbers. The transition from the Langmuir/z mode to the Langmuir/whistler mode near ome ga(p)=Omega(e) is rapid. In addition, the effects on wave dispersion and po larization after adding a beam are investigated. Applications of this theor y to magnetized Langmuir waves in Earth's foreshock and the solar wind, to waves observed near the plasma frequency in the auroral regions, and to sol ar type III bursts are discussed. (C) 2000 American Institute of Physics. [ S1070-664X(00)00608-X].