Most low temperature deformation machines, working down to 1-3-4 K ~-7 are designed to study a single specimen on each cooling. Multi-position attachments have been developed for studies of extension, a' 9 We describe below a low temperature deformation machine in which up to nine specimens can be tested in compression simultaneously for loads up to 200 kg. It consists of a deformation device housed in a cryostat, a measuring system, and a multi-position attachment. The main components of the deformation part are shown in Figure . Axially symmetrical compressive forces between the moving tube, 4, with a transverse strip and the fixed rod, 2, With the stand on which the specimen 1 is placed, are produced by a kinematic system. The base of the machine is the support plate, 10, which has fastened to it the electric motor and reduction gear providing a couple to the worm, 5. The design of the reduction gear is copied from the relaxometer of Regel 1 and Dubov 1 o and enables 18 deformation rates in the range 12-9 x 10 -s nun rain -~ to be obtained. The couple from the worm is applied to worm wheel, 6, which engages on the inside with the load tube, 4, and gives the latter a vertical translational motion. The compressive force is transmitted to dynamometer 7 from specimen 1 through the inner rod, 2, firmly attached to the movable frame, 12, suspended with it on sphere 8. Any slant, due to possible non-parallelness of the specimen ends can be taken up by the free suspension of the rod.
The system is sealed with three rubber gland-type washers, 9, compressed by nuts. The dewar is fixed in the way used by Pustovalov et al.7 The loading tube, 4, is sealed on its outer diameter and for sealing rod 2 a soft bellows, 11, is soldered between tube 4 and the stuffing box. This disposition of the deformation components and dynamometer means that the measuring parts operate under normal conditions (T = 300 K and atmospheric pressure), so that no error is introduced into the measured force. There is no frictional loss between specimen and dynamometer since rod 2 remains practically stationary on deformation. It moves only by microns because of deforma. tion of the rigid dynamometer, 7, and even this movement does not take place by sliding in the packing, but through the flexibility of the bellows, 11.
The force is measured by the tubular dynamometer, 7, which has strain gauges stuck to its surface, forming a strain gauge bridge. Apart from the bridge, the measuring system contains an EPP-09 potentiometer and an attachment with a resistance bank so that the bridge can be shunted to change the sensitivity over a wide range. The principles of the measuring and recording of the load is similar to that described by Pustovalov et al. 7