  Little-Parks oscillations are observed in a system of 110 series-connected
aluminum rings 2000 nm in diameter with the use of measuring currents from 10
nA to 1000 nA. The measurements show that the amplitude and character of the
oscillations are independent of the relation between the measuring current and
the amplitude of the persistent current. By using asymmetric rings, it is
demonstrated that the persistent current has clockwise or contra-clockwise
direction. This means that the total current in one of the semi-rings may be
directed against the electric field at measurement of the Little-Parks
oscillations. The measurements at zero and low measuring current have revealed
that the persistent current, like the conventional circulating current, causes
a potential difference on the semi-rings with different cross sections in spite
of the absence of the Faraday's voltage.
