论文标题
在放牧角磁场的壁附近等离子体中血浆中离子速度分布的大型陀螺轨道模型
Large gyro-orbit model of ion velocity distribution in plasma near a wall in a grazing-angle magnetic field
论文作者
论文摘要
在磁场$ \ vec {b} $上以小角度（$α\ ll 1 $（在弧度）向目标倾斜的磁场$ \ vec {b} $，在血浆中的离子分布函数显示了一个模型。假设是绝热的电子，需要$α\ gg \ sqrt {zm _ {\ rm e}/m _ {\ rm i}} $其中$ m _ {\ rm e} $和$ m _ {\ rm i} $是电子和$ s的$ s nist occunt y rm ies is os，存在电场$ \ vec {e} $以驱除电子，因此静电电位$ ϕ $的特征大小是由电子温度$ t _ {\ rm e} $，$ e d _ {\ sim t _ {\ sim t _ {\ rm e} $设定的，其中$ e $是Proton Charge。 debye长度之间的渐近刻度分离，$λ_ {\ rm d} = \ sqrt {ε_0t _ {\ text {e}}/e^2 n _ {\ text {\ text {e}}} $ m _ {\ rm i}（zt _ {\ rm e}+t _ {\ rm i}）}}/（zeb）$，以及碰撞区域$ d _ {\ rm c} =αλ_{\ rm mfp} $的大小是ρ_ {\ rm s} \ ll d _ {\ rm c} $。这里$ε_0$是自由空间的介绍性，$ n _ {\ rm e} $是电子密度，$ t _ {\ rm i} $是离子温度，$ b = | \ vec {b} | $ and $λ_{\λ_{\ rmmfp} $是collis collis collis collis collis free wree path an c的collis nip and collis niv。离子分布函数的形式是在距离墙壁$ x $的情况下假定的，因此$ρ_{\ rm s} \ ll x \ ll d _ {\ rm c} $。为离子轨迹和目标处的离子分布函数求解$ ϕ（x）$的自洽解决方案。此处介绍的模型允许绕过$ ϕ（x）$的数值解，并导致目标处的离子分布函数的分析表达式。它假设$τ= t _ {\ rm i}/（zt _ {\ rm e}）\ gg 1 $，并且忽略离子轨迹上的电力直到靠近目标。对于$τ\ gtrsim 1 $，该模型可为目标在目标的能量角度分布提供快速近似。这些可用于做出溅射预测。
A model is presented for the ion distribution function in a plasma at a solid target with a magnetic field $\vec{B}$ inclined at a small angle, $ α\ll 1$ (in radians), to the target. Adiabatic electrons are assumed, requiring $α\gg\sqrt{Zm_{\rm e}/m_{\rm i}} $ where $m_{\rm e}$ and $m_{\rm i}$ are the electron and ion mass respectively, and $Z$ is the charge state of the ion. An electric field $\vec{E}$ is present to repel electrons, and so the characteristic size of the electrostatic potential $ϕ$ is set by the electron temperature $T_{\rm e}$, $eϕ\sim T_{\rm e}$, where $e$ is the proton charge. An asymptotic scale separation between the Debye length, $λ_{\rm D}=\sqrt{ε_0 T_{\text{e}}/e^2 n_{\text{e}}}$, the ion sound gyroradius $ρ_{\rm s}=\sqrt{ m_{\rm i}(ZT_{\rm e}+T_{\rm i})}/(ZeB)$, and the size of the collisional region $d_{\rm c} = αλ_{\rm mfp}$ is assumed, $λ_{\rm D} \ll ρ_{\rm s} \ll d_{\rm c}$. Here $ε_0$ is the permittivity of free space, $n_{\rm e}$ is the electron density, $T_{\rm i}$ is the ion temperature, $B= |\vec{B}|$ and $λ_{\rm mfp}$ is the collisional mean free path of an ion. The form of the ion distribution function is assumed at distances $x$ from the wall such that $ρ_{\rm s} \ll x \ll d_{\rm c}$. A self-consistent solution of $ϕ(x)$ is required to solve for the ion trajectories and for the ion distribution function at the target. The model presented here allows to bypass the numerical solution of $ϕ(x)$ and results in an analytical expression for the ion distribution function at the target. It assumes that $τ=T_{\rm i}/(ZT_{\rm e})\gg 1$, and ignores the electric force on the ion trajectory until close to the target. For $τ\gtrsim 1$, the model provides a fast approximation to energy-angle distributions of ions at the target. These can be used to make sputtering predictions.
