SPLIT OF THE ALFVEN-WAVE PACKET IN A DISSIPATIVE PLASMA

We have experimentally found that ion-neutral collisions in a magnetiz ed plasma cause a drastic change in the dispersion relation of the Alf ven wave at frequencies below the ion-cyclotron frequency. In a consec utive experiment we have also found that the measured average velocity of the wave packet does not obey the conventional group velocity that exceeds the velocity of light, but obeys a new defined group veracity that is much lower than the velocity of light. Furthermore, when the initial central frequency of the wave packet is just located on the an omalous dispersion range of frequency, the wave packet splits, when pr opagating along the magnetic field, into two new wave packets with cen tral frequencies being higher and lower than the initial central frequ ency. One of the new packets with lower central frequency is confirmed to be the shear Alfven wave and the other the compressional Alfven wa ve; the behaviour of these new wave packets can also be explained by o ur new theory.