  A prototype of a novel superconductive undulator with a period length of 3.8
mm is described. The undulator is 100 periods long. In the first tests
described in this paper the undulator was cooled in a helium bath and it was
shown that it can be operated as expected with a maximum current of 1400 A.
Afterwards the undulator field was measured with a miniature Hall probe with an
active area of (100x100)x10^-6 m^2. Calculated and measured field distributions
are in good agreement. A cryostat for a beam test at Mainz microtron MAMI was
built in which liquid helium cools indirectly the in-vacuum undulator. At the
moment the cryostat is tested and optimized.
