Some details of vacuum system designs of beam transport lines are pres
ented. The effect of gas desorption on vacuum equilibrium and stabilit
y and ion-induced pressure instability in the beam transport lines are
discussed. Main vacuum relationships are also given as a basis for un
derstanding the vacuum system configuration of beam transport lines. R
esidual gas spectra together with specific outgassing rates of main ma
terials used for construction of beam transport lines are shown. (C) 1
997 Elsevier Science Ltd. All rights reserved.