Consider a perfect quasi-symmetric field
$$
B(\chi) = B_0 + \epsilon_0 \cos{\chi} ; ,
$$
with helical angle
$$
\chi = M\vartheta - N\varphi \quad , N=N_p ; .
$$
The number of field periods is denoted by $N_p$. If we apply a pertubation of the form
$$
\delta B = \epsilon_1 \cos(m\vartheta + n\varphi)
$$
where $n \neq N_p$ the code
- detects a minimum line away from $2\pi k$
- maxima are not longer symmetric under the shifted field line label
Fix the issue by e.g.
- adding a safety mechanism that such field must not enter
- lifting the requirement of $N = k N_p$
Consider a perfect quasi-symmetric field
with helical angle
The number of field periods is denoted by$N_p$ . If we apply a pertubation of the form
where$n \neq N_p$ the code
Fix the issue by e.g.