1.- Introduction. Stellarator optimization takes into account several criteria, including neoclassical transport and stability (see e. g.1). Mercier criterion provides stability against interchange modes and is usually considered among the optimization criteria~2. The magnetic well, related to the plasma shape, is a key stabilizing ingredient and, hence, the optimized configurations are usually complex and must be created by complicated coils, difficult to build and to maintain, which is especially relevant for a stellarator-based reactor, where the operations of maintenance must be performed using remote handling techniques. Therefore the relaxing of such a criterion can help to design simpler and cheaper stellarators.
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