\def\title{Toroidal magnetic field system}

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\GWiwrapfigure{r}{0.5\tw}{width=0.5\tw}{Tokamak/ToroidalMagneticFieldCoils/OPmodel.jpg}{Toroidal magnetic field system}
The vacuum chamber is wrapped by poloidal coils generating toroidal magnetic field $B_t$ along the torus (in the toroidal direction). Since the current in the toroidal magnetic field coils is generated by capacitor discharging, the time evolution of the field is of a harmonic shape bellow \GWPhysQuantValueWithName{Diagnostics/Standard/ToroidalMagneticField/Maximum}. The toroidal magnetic field decreases with increasing major radius $R$, $B_{t}\sim 1/R$ due to the toroidal geometry. As a consequence, the grad-$B$ drift $\nabla B_t \times \vec{B_t}$ separates ions and electrons and creates an electric field $\vec{E}_{rad}$ perpendicular to $\vec{B}_{t}$. The resulting $\vec{E}_{rad}\times\vec{B}_{t}$ drift causes a collective motion of charged particles, making the plasma unstable.
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Toroidal magnetic field (B$_t$) in tokamak is created by external coils turned poloidally around the \ref{Tokamak/VacuumVessel}. There are 28 toroidal field coils each with 11 turns with the total inductance \GWPhysQuantValueWithName{Tokamak/VacuumVessel/TechnologicalQuantities/Inductance}. Discharging capacitor battery into this inductance results in induction of sinusoidal damped toroidal magnetic field B$_T$ with the peak value max 0.4 T. Toroidal field is not constant over the duration of the GOLEM discharge. \cite{DuranPhD}
The inner diameter of the coils is 33.4 cm, and the outer diameter is 40 cm.
}