SU300137A1 - Superconducting Electromagnet Syncrotron - Google Patents

Description

As is well known, in ring accelerators of particles such as a synchrotron (proton or electron), electromagnets are used to rotate and focus accelerated particles, which create in the area occupied by the beam of accelerated particles a highly inhomogeneous magnetic field having a plane (anti ) symmetry, which coincides with the orbit plane, is the median plane. Median-plane magnetic fields are used in accelerators with substantially spiral orbits (cyclotron, phasotron, microtron), in low-focusing synchrotrons, and in synchrotrons and storage rings with high focusing.

In synchrotrons and storage rings with a strong focusing, the symmetry of the magnetic field relative to the median plane leads, in addition to the well-known conveniences, to a large under-utilization of the magnitude of the field.

Due to the large magnitude of the gradient, magnetic induction in the region occupied by the orbits is obtained significantly less than in the non-operating region, between the edges of the poles.

One way to overcome this drawback is to separate the functions of the rotation and focusing of particles between the wrapping magnets and the quadrupole lenses. The disadvantage of this method is doubling the number of magnets and the complexity of their power supply system.

The proposed superconducting electromagnet of the synchrotron makes it possible to reduce field inhomogeneity.

The essence of the proposal consists in the rejection of the use of magnetic fields antisymmetric with respect to the plane of the central orbit (Fig. 1), and the transition to the use of fields symmetric with respect to the plane that is perpendicular to the plane of the orbits. The principle of construction of the corresponding non-iron (in particular, superconducting) magnet is shown in FIG. 2. This magnet creates a vertical wrapping field and a quadrupole focusing field rotated by 45 ° compared to a conventional quadrupole field used for focusing in variable gradient synchrotrons.

Positions I, 2, 3 are the distribution of amperages of the corresponding harmonics.

To create a field of the usual type, a system is used (Fig. 2, a), which is characterized by the addition of the maxima of the amperbit harmonics, which create the dipole and quadrupole field components.

can be obtained by applying one or several windings that create dipole and quadrupole components of the field, oriented so that the plane of symmetry of the resulting field is perpendicular to the plane of rotation of the particles. For example, in the case of the use of dipole and quadrupole windings, places with zero density of turns of quadrupole winding should be located in maxima or zero density of turns of dipole winding.

The sign of the gradient of the quadrupole component of the proposed magnets alternates along the orbit in the same way as in the conventional system (see Fig. 1) of alternate focusing along the radius and vertical.

In this system, alternating focusing is obtained along a diagonal, i.e., at an angle of + 45 ° with respect to the axes x, z, if the magnets of the proposed type are the same length as ordinary magnets.

Magnetic fields of the corresponding type can be obtained both with the help of iron magnets and ironless, for example, superconducting magnets (see Fig. 2).

The advantage of magnets of the proposed type compared to conventional ones is that with the same gradient-to-field ratio at the center, the field at the edges of the working area in the new magnets is smaller than in conventional ones: in conventional magnets the quadrupole component is parallel to the wrapping field and in new magnets these components are different in direction by 45 °. This leads to a decrease in induction at the edges of the poles of iron magnets or to a decrease in induction in the winding of iron-free magnets.

The specified property of such magnets allows increasing the maximum energy of particles at a given accelerator radius (and a corresponding increase in the number of ampere turns of the magnet) or reducing the power of the magnet at a given accelerator radius and a given maximum particle energy, or increasing the system’s admittance by increasing the gradient to field ratio.

This system creates a strong focus, which in the approximation of a smoothed motion does not differ from the usual; it has, therefore, other necessary properties:

donuts the formation of short and long (consistent) intervals;

has tolerances for field and gradient errors, as well as non-linearities, equal to the usual order of magnitude;

has a high orbital compaction rate;

allows the measurement of the position of the equilibrium orbit and the number of betatron oscillations, as well as the performance of the correction of the field, gradient and nonlinearity by conventional methods taking into account the specificity of the structure (rotation by 45 °); possible input and output of a beam of accelerated particles.

Subject invention

A superconducting electromagnet of a synchrotron with a focusing variable gradient of a magnetic field with combined functions of rotation and focusing of particles, containing one or more windings creating a dipole and quadrupole field components, characterized in that

reducing the inhomogeneity of the zero, ampere-turns of the windings are distributed so that the plane of symmetry of the created field is perpendicular to the plane of the particle's inversion, for example, so that places with zero density of turns

quadrupole windings are located in maxima or zero density turns of the dipole winding.

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