350
F. Bordry et al.
EBS light source [4], and even as spectrometers as for example in the nTOF
experiment at CERN [5].
8.1.2.6 Solenoids
Solenoids are made by electrical conductors wound in the form of a helix. The
magnetic field induction inside an ideal solenoid is parallel to the longitudinal axis
and its intensity is B = μ 0 NI/l where NI is the total number of ampere-turns and l
the solenoid length. By introducing the coil thickness t, the formula can be written
as B = μ 0 Jt, where J is the current density.
Solenoids can be built as ironless magnets or can have an external ferromagnetic
yoke, used for shielding and to increase the magnetic field uniformity particularly
at the solenoid extremities.
The design and construction of solenoids, thanks to their use in many electrical
and electro-mechanical devices, is well assessed since more than a century. A
comprehensive treatment of solenoid electromagnets was compiled by C. Underhill
already in 1910. The treatment issued by Montgomery in 1969 is still a reference [6]
nowadays, in spite of new materials now available in particular for wire dielectric
insulation and for the containment of stresses.
In solenoids the electromagnetic forces produced by the interaction between
the magnetic field and the currents in the coils can reach extremely high values
capable of breaking the wires or even, especially for pulsed magnets, leading to an
explosion of the device. Their design should consider conductor characteristics and
reinforcements, winding tension during manufacture and the containment structure.
8.1.3 Superconducting Magnets
Superconducting magnet technology has been instrumental to the realization of the
largest particle accelerators on Earth. Table 8.4 reports the main characteristics of
the four large scale hadron accelerators built and operated since the beginning of
superconducting magnet technology for accelerators. In parallel, superconductivity
has fostered the construction of high field and large volume detector magnets that
have become commonplace in high energy physics. The first such detector magnet
was installed at Argonne National Laboratory, and operated in the mid 1960s as an
instrument in the Zero Gradient Synchrotron (ZGS) [11]. Atlas [12] and CMS [13]
at the LHC are the latest and most impressive example of superconducting detector
magnets.
The prime difference between superconducting and normal conducting magnets
is in the way the magnetic field induction is generated. While in normal conducting
magnets the field is dominated by the magnetization of the iron yoke, in their
superconducting “siblings” the field is generated by a suitable distribution of
currents, properly arranged around the beam aperture. This is possible because a
F. Bordry et al.
EBS light source [4], and even as spectrometers as for example in the nTOF
experiment at CERN [5].
8.1.2.6 Solenoids
Solenoids are made by electrical conductors wound in the form of a helix. The
magnetic field induction inside an ideal solenoid is parallel to the longitudinal axis
and its intensity is B = μ 0 NI/l where NI is the total number of ampere-turns and l
the solenoid length. By introducing the coil thickness t, the formula can be written
as B = μ 0 Jt, where J is the current density.
Solenoids can be built as ironless magnets or can have an external ferromagnetic
yoke, used for shielding and to increase the magnetic field uniformity particularly
at the solenoid extremities.
The design and construction of solenoids, thanks to their use in many electrical
and electro-mechanical devices, is well assessed since more than a century. A
comprehensive treatment of solenoid electromagnets was compiled by C. Underhill
already in 1910. The treatment issued by Montgomery in 1969 is still a reference [6]
nowadays, in spite of new materials now available in particular for wire dielectric
insulation and for the containment of stresses.
In solenoids the electromagnetic forces produced by the interaction between
the magnetic field and the currents in the coils can reach extremely high values
capable of breaking the wires or even, especially for pulsed magnets, leading to an
explosion of the device. Their design should consider conductor characteristics and
reinforcements, winding tension during manufacture and the containment structure.
8.1.3 Superconducting Magnets
Superconducting magnet technology has been instrumental to the realization of the
largest particle accelerators on Earth. Table 8.4 reports the main characteristics of
the four large scale hadron accelerators built and operated since the beginning of
superconducting magnet technology for accelerators. In parallel, superconductivity
has fostered the construction of high field and large volume detector magnets that
have become commonplace in high energy physics. The first such detector magnet
was installed at Argonne National Laboratory, and operated in the mid 1960s as an
instrument in the Zero Gradient Synchrotron (ZGS) [11]. Atlas [12] and CMS [13]
at the LHC are the latest and most impressive example of superconducting detector
magnets.
The prime difference between superconducting and normal conducting magnets
is in the way the magnetic field induction is generated. While in normal conducting
magnets the field is dominated by the magnetization of the iron yoke, in their
superconducting “siblings” the field is generated by a suitable distribution of
currents, properly arranged around the beam aperture. This is possible because a