Barriga-Carrasco Manuel D
E.T.S.I. Industriales, Universidad de Castilla-La Mancha, E-13071 Ciudad Real, Spain.
Phys Rev E Stat Nonlin Soft Matter Phys. 2013 Oct;88(4):043107. doi: 10.1103/PhysRevE.88.043107. Epub 2013 Oct 30.
According to dielectric formalism, the energy loss of the heavy ion depends on its velocity and its charge density. Also, it depends on the target through its dielectric function; here the random phase approximation is used because it correctly describes fully ionized plasmas at any degeneracy. On the other hand, the Brandt-Kitagawa (BK) model is employed to depict the projectile charge space distribution, and the stripping criterion of Kreussler et al. is used to determine its mean charge state [Q]. This latter criterion implies that the mean charge state depends on the electron density and temperature of the plasma. Also, the initial charge state of the heavy ion is crucial for calculating [Q] inside the plasma. Comparing our models and estimations with experimental data, a very good agreement is found. It is noticed that the energy loss in plasmas is higher than that in the same cold gas cases, confirming the well-known enhanced plasma stopping (EPS). In this case, EPS is only due to the increase in projectile effective charge Q(eff), which is obtained as the ratio between the energy loss of each heavy ion and that of the proton in the same plasma conditions. The ratio between the effective charges in plasmas and in cold gases is higher than 1, but it is not as high as thought in the past. Finally, another significant issue is that the calculated effective charge in plasmas Q(eff) is greater than the mean charge state [Q], which is due to the incorporation of the BK charge distribution. When estimations are performed without this distribution, they do not fit well with experimental data.
根据介电形式理论，重离子的能量损失取决于其速度和电荷密度。此外，它还通过目标的介电函数依赖于目标；这里使用随机相位近似，因为它能正确描述任何简并度下的完全电离等离子体。另一方面，采用布兰特 - 北川（BK）模型来描述弹丸电荷的空间分布，并使用克劳斯勒等人的剥离准则来确定其平均电荷态[Q]。后一个准则意味着平均电荷态取决于等离子体的电子密度和温度。此外，重离子的初始电荷态对于计算等离子体内的[Q]至关重要。将我们的模型和估计值与实验数据进行比较，发现吻合度非常高。值得注意的是，等离子体中的能量损失高于相同冷气体情况下的能量损失，这证实了众所周知的增强等离子体阻止（EPS）。在这种情况下，EPS仅归因于弹丸有效电荷Q(eff)的增加，Q(eff)是通过在相同等离子体条件下每个重离子与质子的能量损失之比获得的。等离子体与冷气体中有效电荷的比值大于1，但并不像过去认为的那么高。最后，另一个重要问题是，计算得到的等离子体中有效电荷Q(eff)大于平均电荷态[Q]，这是由于纳入了BK电荷分布。如果在没有这种分布的情况下进行估计，它们与实验数据的拟合效果不佳。
