tokens: flow pattern is consistent across the diamagnetic cavity boundary in the CSE frame, we suggest that the flow pattern inside the cavity is determined by the flow outside, depending on the local plasma and magnetic field conditions. Fig. 7 Summary of flow pattern of the accelerated ions inside and outside the diamagnetic cavity in the YZ plane of ( a ) the CSEQ frame and ( b ) the CSE frame. The dark gray object at the center of each figure indicates the comet nucleus, and the surrounding light gray shaded area is the diamagnetic cavity. The view of these figures is from the Sun, and the four regions depending on the clock angle of the Rosetta position are also shown. In each region, a main tailward flow and its aberration component are shown by a cross and an arrow, respectively. Figure 8 summarizes the ion flow pattern inside and outside the diamagnetic cavity in the CSE frame. The aberration pattern of the accelerated ions in the - Z CSE direction near the XZ plane seen in Fig. 8 a suggests that they are mass-loaded by local cold cometary ions, which is similar to the mass-loading of the solar wind ( Behar et al. 2016a , b , 2017 ). The mass-loading of the accelerated cometary ions would result in an acceleration of the local cold cometary ions in the + Z CSE direction due to the conservation of momentum in the system, but we did not detect such a flow pattern from ICA data. This suggests that their energy is very low, which would be out of the energy range in this study (40 eV), or more likely, the density of the accelerated ions is much lower than the local cometary plasma, meaning that the earning momentum for the cold cometary ions is negligible. Fig. 8 Summary of the flow pattern of the accelerated cometary ions inside and outside the diamagnetic cavity in ( a ) the XZ plane and ( b ) the XY plane of the CSE frame. Near the XY plane of the CSE frame ( Fig. 8 b), the accelerated ions flow tailward with an anti-cometward aberration. This indicates that the accelerated ions are deflected around the diamagnetic cavity. The mechanism that produces this flow pattern is still unknown, but the accelerated ions may have been deflected when they flew across the upstream boundaries such as the ion-neutral collisionopause or the SWIC boundary. Another possibility is the aforementioned ambipolar electric field that points outward from the nucleus ( Odelstad et al. 2018 ; Bercic et al. 2018 ). This electric field may cause the tailward-flowing ions to be deflected around the diamagnetic cavity, which results in the anti-cometward aberration of the flow in the XY plane in the CSE frame. As seen in observations, the flux of these ions inside the cavity is nearly one order of magnitude lower than that outside the cavity. This suggests that the accelerated ions are only partly transferred from the outside into the inside of the diamagnetic cavity. There may be an energy-filtering effect in the cavity boundary. If the ion transmission into the cavity is
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