Electrostatic particle simulations of the WDL in the auroral plasma including the effects of up-flowing ions

An upward beam of hot ions which originates in the ionosphere is commonly observed in and above the region of auroral particle acceleration. Past simulations of the weak double layer (WDL) have only included magnetospheric hot electrons and ionospheric cold ions. We simulated the formation of the WDL numerically and more realistically using a one dimensional electrostatic code. We modeled magnetospheric hot electrons, ionospheric cold ions and hot ionospheric beam ions in the system. The existence of the hot ion beam modifies the characteristics of the WDL, its magnitude of the potential drop and lifetime. We investigated the variation in the character of the WDL for different fractions of the hot ion beam component. The magnitude of the potential jump of the WDL was found to decrease but the lifetime of the WDL increase as this proportion increased. The existence of a critical value of the ratio of the hot beam ions to the cold ions, above which electrons cannot be accelerated effectively and which places an upper limit on the altitude of auroral particle acceleration region has also been shown.