INSTALLATION OF THE ELECTROMAGNET OF A 300 MeV SYNCHROTRON

V. N. Eponeshnikov, P. P. Krasnososenkikh, V. N. Kuzmin,
Yu. K. Petrov

The electromagnet of the 300 MeV synchrotron was installed on a base consisting of four steel plates welded to channels, which, in turn, are fastened to the foundation by means of anchor bolts. A check of the accuracy of the placement of the bases in height and plan after their final installation showed that, in height, the bases were set with an accuracy of \(\pm 3.5\) mm. The radial dimensions of the support arcs were maintained with an accuracy of \(\pm 1.5\) mm. The height position of the bases was checked with a geodetic level, and the radial position of the arcs with the aid of a special compass device consisting of a steel plate installed at the center of the magnet, with four holes whose centers form a square with side 506 mm, and a compass inserted into the holes of the plate. The holes in the plate forming the square were drilled with an accuracy of \(\pm 0.1\) mm along the side of the square and \(\pm 0.15\) mm along the diagonal. It was not expedient to seek a more accurate height-and-plan position of the support plates, since the dimensions of the electromagnet blocks had been maintained with approximately the same tolerances.

For installation and subsequent checking of the sector angles, a coordinate system was developed. For this purpose, with the aid of a theodolite, two mutually perpendicular directions—I—I and II—II (Fig. 1)—were established, passing through the centers of the holes of the compass plate. From these directions the angles \(41^\circ 41'\) (one half of the calculated sector angle) were laid off, and the points \(Ю_1, Ю_2, В_1, В_2, З_1, З_2, С_1, С_2\) were set out. The theodolite was then centered successively on each of the points thus set out, and marks were made on the plates. In this way, on each base plate of the electromagnet, scribe marks were obtained corresponding to the calculated sector angle \(83^\circ 28'\).

The required accuracy of the height-and-plan position of the electromagnet during installation was achieved by means of pressboard shims under the individual blocks (both in height and in radius).

On each block, measurements of the phase inhomogeneity and residual field had first been carried out. On the basis of these measurements, the arrangement of the blocks in the electromagnet was selected so as to obtain minimal distortions of the electron orbit. The installation of the electromagnet was carried out in the following sequence. In accordance with the measurements of the height-and-plan position of the bases, pressboard shims were made for each block according to the hei-

…both tangentially and radially. All six blocks of a sector were placed on the support plate at once. The blocks were tightened to one another and drawn down to the base. Magnetizing windings were put on the upper and lower poles; these were fed with direct current, and the median surface was measured with an instrument [1]. If the measurements showed that the deviation of the median surface was greater than permissible, the entire sector was reassembled, and by changing the thickness of the shims it was ensured that the deviation of the median surface did not exceed \(\pm 1.5\) mm.

Fig. 1

In this way all four sectors were assembled. After all the sectors had been mounted, control measurements of the median surface were carried out. The results of these measurements are shown in Fig. 2. The sector angles were set according to the scribed marks, as mentioned above, applied to the support plates. Control measurements of the sector angles with a theodolite after completion of the installation showed that the deviations of the angles from the calculated position were \(+0^\circ 1'30''\).

The power windings of the electromagnet were finally secured on the sectors by means of brass jacks (in the window of the electromagnet and on the outer part). At the ends the windings were fastened with brackets. The sections of the windings of each sector were connected to one another, and the intersector connections were made in four terminal boards installed inside the sectors.

To correct the principal parameters of the magnetic field of the synchrotron, correcting windings are provided for correcting the sector angles, the first and second harmonics, the position of the median surface, and the magnetic-field falloff index.

Fig. 2

The windings for correcting the sector angles were wound on the back of the yoke of each end block; for this purpose, grooves 5 mm deep were cut in them. The turns on the end blocks were wound before the blocks were installed in the electromagnet; all the remaining pole and yoke compensating windings were wound after complete assembly of the electromagnet. The ends of all turns were brought out to terminal boards installed on the end plates of each sector.

REFERENCES

1. V. N. Kuz’min, Yu. K. Petrov. A device for measuring the median surface of the magnetic field in an accelerator. Proceedings of the Third Interuniversity Conference on Electron Accelerators, Tomsk, 1959.