Simpson J A, Hamilton D C, Lentz G A, McKibben R B, Perkins M, Pyle K R, Tuzzolino A J, O'gallagher J J
Science. 1975 May 2;188(4187):455-9. doi: 10.1126/science.188.4187.455.
During the December 1974 Pioneer 11 Jupiter encounter our experiment provided measurements of Jovian energetic protons and electrons both in the magnetic equatorial zone and at previously unexplored high magnetic latitudes. Many of the observations and conclusions from the Pioneer 10 encounter in 1973 were confirmed, with several important exceptions and new findings. We report evidence from Pioneer 11 for protons ( approximately 1 million electron volts) of Jovian origin in interplanetary space. In the outer magnetosphere particle intensities at high magnetic latitudes were comparable to those observed in the equatorial zone, and 10-hour variations in particle intensities and spectra were observed at both high and low magnetic latitudes. Therefore, confinement of particles in the outer magnetosphere to a thin equatorial magnetodisc is adequate neither as a description of the particle distribution nor as a complete explanation of the 10-hour variations. Pioneer 11 data support a model in which the intensity varies with a 10-hour period in phase throughout the sunward side of the magnetosphere and is relatively independent of position within the magnetosphere. Transient, highly anisotropic bursts of protons with energies of approximately 1 million electron volts observed near the orbit of Ganymede suggest local acceleration in some regions of the magnetosphere. In the inner core where particles are stably trapped, a maximum in the high-energy nucleonic flux was again found, corresponding to the Pioneer 10 maximum at approximately 3.4 Jupiter radii (R(J)), which is apparently a persistent feature of, the inner radiation zone. In addition, Pioneer 11 data indicate two more local maxima in the nucleonic flux inside 3.4 R(J), one of which may be associated with absorption by Amalthea, and a maximum intensity at 1.9 R(J) more than 20 times that at 3.4 R(J), The flux of relativistic electrons reached a maximum on the magnetic equator at 1.8 R(J), only slightly less its closest approach at 3.1 R(J).
1974年12月“先驱者11号”飞掠木星期间,我们的实验对木星高能质子和电子在磁赤道区域以及此前未探测过的高磁纬度地区进行了测量。1973年“先驱者10号”飞掠木星时的许多观测结果和结论得到了证实,但也有几个重要的例外和新发现。我们报告了“先驱者11号”获得的证据,证明在行星际空间中存在源自木星的质子(能量约为100万电子伏特)。在外磁层,高磁纬度处的粒子强度与赤道区域观测到的强度相当,并且在高、低磁纬度处均观测到粒子强度和能谱的10小时变化。因此,将外磁层中的粒子限制在一个薄的赤道磁盘内,既不足以描述粒子分布,也不能完全解释10小时的变化。“先驱者11号”的数据支持这样一个模型,即强度在磁层向日侧整个区域内以10小时周期同相位变化,并且相对独立于磁层内的位置。在木卫三轨道附近观测到能量约为100万电子伏特的质子的瞬态、高度各向异性爆发,这表明在磁层的某些区域存在局部加速。在粒子被稳定捕获的内核中,再次发现了高能核子通量的最大值,对应于“先驱者10号”在约3.4木星半径(R(J))处的最大值,这显然是内辐射带的一个持久特征。此外,“先驱者11号”的数据表明,在3.4 R(J)以内的核子通量还有另外两个局部最大值,其中一个可能与木卫五的吸收有关,在1.9 R(J)处的最大强度比在3.4 R(J)处的强度大20多倍。相对论电子通量在1.8 R(J)的磁赤道处达到最大值,仅略低于其在3.1 R(J)处最接近时的值。