木星Io通量管中等离子体湍流及低频无线电波的激发和功率

本文对木星极区（1000-6000公里）Io通量管中的等离子体湍流和低频无线电波的激发机制进行了理论分析,并对它们的能量密度作了数值估计。指出:在Io通量管中可能存在着两种主要的不稳定性,一是电流驱导不稳定,这种不稳定可以激发离子声湍流,离子声湍流通过离子的非线性散射可以转化为哨声湍流。这两种湍流的能量密度大致相等,约为10^-17-10^-16焦耳/厘米³。另外一种不稳定性是由于高能粒子沉降引起的束流不稳定,可以激发朗缪尔湍流和迴旋频率等离子体湍流,能量密度分别为10^-17焦耳/厘米³和10^-14焦耳/厘米³的量级。这两种湍流可转化为低频无线电波,最大的能通量可达10^-22-10^-20瓦/厘米²·赫兹。

THE EXCITATION AND POWER OF PLASMA TURBULENCE AND LOW-FREQUENCY RADIO WAVE IN Io FLUX TUBE

In this paper the exeitation and power of plasma turbulence and low-frequency radio wave in Io flux tube are discussed. We indicate that there are two possible instabilities in Io flux tube. One is current drive instability which can excite ionsound turbulence, and ion-sound turbulence, through non-linear scattering by ions can be changed into whistles. The other one is beam instability caused by energetic precipi-ting particles, which can excite Langinuir turbulence and gyro-frequency plasma turbulence which can generate low-frequency radio wave both at frequencies close to 2ωpe and at frequencies close to ωHe. Finally, the power of these plasma turbulences and low-frequency radio waves are calculated.