Patent ID: 6914248

Claim:
A method of manipulating charged particles of a beam of charged particles by a magnetic field, the method comprising: operating a magnetic field generating apparatus having a magnetic-flux-carrying body made of a material with a high permeability number, and at least one current conductor located adjacent to the magnetic-flux-carrying body, and operating the magnetic-flux-carrying body at an operating temperature, wherein the permeability number of the material is temperature dependent, and the material and the operating temperature are chosen such that the operating temperature is within a temperature range, in which the following applies: μ max - μ min μ max · Δ ⁢ ⁢ T = c , ⁢ with ⁢ ⁢ c < 3 · 10 - 5 ⁢ K - 1 wherein μ max is a maximum value of the permeability number in the temperature range, μ min is a minimum value of the permeability number in the temperature range, and ΔT is a width of the temperature range.