  Magnetorotational instability (MRI) is one of the most important and most
common instabilities in astrophysics, it is widely accepted that it serves as a
source of turbulent viscosity in accretion disks -- the most energy efficient
objects in the Universe. However it is very difficult to bring this process
down on earth and model it in a laboratory experiment. Several different
approaches have been proposed, one of the most recent is PROMISE
(Potsdam-ROssendorf Magnetorotational InStability Experiment). It consists of a
flow of a liquid metal between two rotating cylinders under applied
current-free spiral magnetic field. The cylinders must be covered with plates
which introduce additional end-effects which alter the flow and make it more
difficult to clearly distinguish between MRI stable and unstable state. In this
paper we propose simple and inexpensive improvement to the PROMISE experiment
which would reduce those undesirable effects.
