EBIS and EBIT - Spallation Neutron Source

Magnetic Emittance
The conservation of the magnetic moment (Busch‘s theorem) results in skew trajectories outside of
the magnetic field. Treating the extracted beam as a round one, results in an additional „magnetic“ emittance:
For modern EBIS and EBIT B z =3T and U 0 =20 kV, producing bare light nuclei we then obtain:
r (m)
10 -3
10 -4
abs (µ) *
5.2
5.2 x 10 -2
EBIS beams are usually smaller than 1 mm, therefore the magnetic emittance will be negligible.
For EBIT with 100 µ beams even more.
2
2eq
Br
abs
4 M U 0
Note that dimension µ for the emittance gives the same numbers as the old fashioned mm x mrad *)
m *) R.Becker and W.B.Herrmannsfeldt, Wha Pi and mrad?, Rev. Sci. Instrum.77 (2006) 03B907