By examining the entropy production in fully kinetic simulations of collisional plasmas, it is shown that the transition from collisional Sweet-Parker reconnection to collisionless Hall reconnection may be viewed as a thermodynamic phase transition. The phase transition occurs when the reconnection electric field satisfies $E=E_D\sqrt{m_e/m_i}$, where $m_e/m_i$ is the electron-to-ion mass ratio and $E_D$ is the Dreicer electric field. This condition applies for all $m_i/m_e$, including $m_i/m_e=1$, where the Hall regime vanishes and a direct phase transition from the collisional to the kinetic regime occurs. In the limit $m_e/m_i\to 0$, this condition is equivalent to there being a critical electron temperature $T_e\approx m_i{\mathrm{\Omega }}_i^2{\delta }^2$, where ${\mathrm{\Omega }}_i$ is the ion cyclotron frequency and $\delta$ is the current sheet half-thickness. The heat capacity of the current sheet changes discontinuously across the phase transition, and a critical power law is identified in an effective heat capacity. A model for the time-dependent evolution of an isolated current sheet in the collisional regime is derived.

中文翻译：

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磁重联中的热力学相变

通过检查碰撞等离子体完全动力学模拟中的熵产生，表明从碰撞 Sweet-Parker 重联到无碰撞霍尔重联的转变可以被视为热力学相变。当重联电场满足时发生相变$乙={乙}_D\sqrt{{米}_{\mathrm{电子}}/{米}_{\mathrm{一世}}}$， 在哪里 ${米}_{\mathrm{电子}}/{米}_{\mathrm{一世}}$ 是电子与离子的质量比和 ${乙}_D$是德雷塞电场。此条件适用于所有${米}_{\mathrm{一世}}/{米}_{\mathrm{电子}}$， 包含 ${米}_{\mathrm{一世}}/{米}_{\mathrm{电子}}=1$，其中霍尔机制消失，并发生从碰撞到动力学机制的直接相变。在极限${米}_{\mathrm{电子}}/{米}_{\mathrm{一世}}\to 0$，这个条件相当于存在一个临界电子温度 ${吨}_{\mathrm{电子}}\approx {米}_{\mathrm{一世}}{\mathrm{\Omega }}_{\mathrm{一世}}^2{\delta }^2$， 在哪里 ${\mathrm{\Omega }}_{\mathrm{一世}}$ 是离子回旋频率和 $\delta$是当前板材的半厚。电流片的热容量在整个相变过程中不连续地变化，并且在有效热容量中确定了临界幂律。推导出碰撞状态下孤立电流片随时间演变的模型。