By a current direction reversal in a subset of the coil packs in a superconductive undulator it is possible to change the period length. The most simple example is a period length doubling schematically shown in fig. .. Here the period length is switched between lambda and 2lambda by reverting the current direction in the yellow coil packs. In line with switching the period length in special cases also the operation mode of the insertion device can be changed, as shown for the example of the ANKA hybrid undulator/wiggler (SCUW) in fig. ... Here, by period tripling the device is switched at the same time from an undulator to a wiggler operation mode where a high on-axis field (3.5T) leads to a continous radiation spectrum extending to the hard X-ray regime (the calculated spectra shown in fig. .. assume the ANKA electron beam parameters).
Forschungszentrum Karlsruhe, LAS and the University of Erlangen and Babcock-Noell (Würzburg, Germany) have launched a joint development project in October 2007, aiming at the technical realisation of the SCUW.