Abstract A numerical method to implement a linearized Coulomb collision operator in the two-weight δ f Monte Carlo method for multi-ion-species neoclassical transport simulation is developed. The conservation properties and the self-adjoint property of the operator in the collisions between two particle species with different temperatures are verified. The linearized operator in a δ f Monte Carlo code is benchmarked with other two kinetic simulations, a δ f continuum gyrokinetic code with the same linearized collision operator and a full-f PIC code with Nanbu collision operator. The benchmark simulations of the equilibration process of plasma flow and temperature fluctuation among several particle species show very good agreement between δ f Monte Carlo code and the other two codes. An error in the H-theorem in the two-weight δ f Monte Carlo method is found, which is caused by the weight spreading phenomenon inherent in the two-weight δ f method. It is demonstrated that the weight averaging method serves to restoring the H-theorem without causing side effect.

中文翻译：

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δf 蒙特卡罗新古典模拟的新多离子物种碰撞算子的基准

摘要 开发了一种在多离子种新经典输运模拟中的二权重δ f Monte Carlo 方法中实现线性化库仑碰撞算子的数值方法。验证了两种不同温度粒子碰撞时算子的守恒性质和自伴随性质。δ f 蒙特卡罗代码中的线性化算子与其他两个动力学模拟进行了基准测试，一个 δ f 连续体陀螺动力学代码具有相同的线性化碰撞算子，一个全 f PIC 代码具有南部碰撞算子。几种粒子种类之间的等离子体流和温度波动的平衡过程的基准模拟显示 δ f 蒙特卡罗代码与其他两个代码之间非常吻合。发现二权重δ f 蒙特卡罗方法的H 定理存在错误，这是由二权重δ f 方法固有的权重扩散现象引起的。结果表明，权重平均方法用于恢复 H 定理而不会引起副作用。