托卡马克（Tokamak），又称环磁机，是一种利用磁约束来实现磁局限融合的环性容器。达到稳定的等离子体均衡需要围绕环面移动的螺旋形状的磁力线。

托卡马克是磁约束装置的几种类型之一，并且是用于生产受控热核核聚变能中的一个最深入研究的候选类型。磁场被用于约束是因为等离子体冷却会使反应停止。而超导托卡马克可长时间约束等离子体。第一个超导托卡马克为俄制的T-7(托卡马克7号)，而T-7由中国改造成HT-7(合肥托卡马克7号为“全”超导托卡马克)。而HT-7U就是现今中国的EAST。托卡马克的一种替代方案是仿星器。

A tokamak (Russian:токамак) is a device that uses a powerful magnetic field to confine plasma in the shape of a torus. Achieving a stable plasma equilibrium requires magnetic field lines that move around the torus in a helical shape. Such a helical field can be generated by adding a toroidal field (traveling around the torus in circles) and a poloidal field (traveling in circles orthogonal to the toroidal field). In a tokamak, the toroidal field is produced by electromagnets that surround the torus, and the poloidal field is the result of a toroidal electric current that flows inside the plasma. This current is induced inside the plasma with a second set of electromagnets.