1. Normal Conducting Magnets
Practical CERN
Normal Conducting Magnets
Thursday 25th & Friday 26th February 2016, 9:00 – 17:00

2. Outline Brief introduction to accelerator magnets
Program and Organization of Magnet Practical Works
Magnet Technology, Production and Testing
Magnetic Measurements

3. Magnetic Field in Particle Accelerators
Particle accelerators: control over moving (charged) particles  need action against mechanical inertia
Equilibrium in the transverse plane:
Centrifugal force vs. Lorentz force
F = mv2/ρ F = q(E + vΛB)
Electrical field quickly shows limits to drive particles with high mass (hadrons) and/or velocity
 qvB = mv2/ρ
Magnetic rigidity: Bρ = mv/q
“A charged particle with constant velocity crossing constant field follows a circular trajectory”

4. Introduction to Magnets
A magnetomotive force creates a magnetic flux
iron
core
coil
magnetic field
NI = R x 
Magnetomotive force is essentially used in the air gap
air
gap
current
Flux = Field x Section
= B x A
(“Field” is actually “Magnetic flux density”)
Courtesy D. Tommasini

5. Introduction to Magnets
Basic principles : constitutive equations
Introduction to Magnets
R = length /(electrical conductivity x section)
R = length/ (magnetic permeability x section)
NI =
 H∙dl (Ampère’s law)
R x (Hopkinson’s law)
B = 0rH
µ0 = 4∙10-7 Tm/A
H can be interpreted as “magnetizing pressure”
In ferromagnetic materials small H creates high B
liron NI
lair
Courtesy D. Tommasini

6. Dipoles Purpose: bend or steer the particle beam
Equation for normal (non‐skew) ideal (infinite) poles: y= ±r (r = half gap height)
Magnetic flux density: By= a1= B0 = const.
‘Allowed’ harmonics: n = 1, 3, 5, 7, ... (= 2n pole errors)
Courtesy T. Zickler

7. Dipoles
Courtesy T. Zickler

8. Quadrupoles Purpose: focusing the beam (in one plane)
Equation for normal (non‐skew) ideal (infinite) poles: 2xy= ±r2(r = aperture radius)
Magnetic flux density: By= a2x
‘Allowed’ harmonics: n = 2, 6, 10, 14, ...
Courtesy T. Zickler

9. Quadrupoles
Courtesy T. Zickler

10. Sextupoles Purpose: correct chromatic aberrations
Equation for normal (non‐skew) ideal (infinite) poles: 3x2y ‐y3= ±r3 (r = aperture radius)
Magnetic flux density: By= a3(x2‐y2)
‘Allowed’ harmonics: n = 3, 9, 15, 21, ...
Courtesy T. Zickler

11. Sextupoles
Courtesy T. Zickler

12. Program and Organization of Practical days
8 to 10 participants
Hands-on practical work in CERN laboratories
Guided by CERN magnet experts
Split into two half-day sessions
Magnet production and testing
Magnetic measurmements

13. Magnet Production and Testing
Introduction to magnet production
Materials for magnets
Magnet components
Manufacturing technologies
Testing and measurement techniques
Practical work in magnet test facility (Meyrin site, bldg. 375)
Participants will perform certification tests and measurements on recently built magnets
Measurements on systems and apparatus using formulae learned during the theoretical courses
Visit the CERN normal conducting magnet prototype workshop “NORMAPRO” (Prévessin site, bldg. 867)
Yoke manufacturing
Coil winding and impregnation

14. Magnet Production Coil winding Yoke manufacturing Coil impregnation
Magnet assembly
Magnet testing

15. Magnet Testing and Practical Applications

16. Magnetic Measurements
Visit the Magnetic Measurement Laboratory
Introduction to different measurement techniques
Field mapping
Rotating coil technique
Stretched wire technique
Practical work in magnetic measurement lab I8
Participants will measure magnets using rotating coil bench
Analysis of mesurement results with CERN experts

17. Visit of Magnetic Measurement Laboratory

18. Field Mapping
Fluxmeter
Hall probe

19. Rotating Coil Measurements
Tangential coil
Radial flux
Radial coil
Tangential flux

20. Streched Wire Measurements

21. Looking forward...
...to welcome you at CERN!