E-mail from Dave MacNair concerning bench measurements made
on SCOR-6 type corrector power supplies, as presently used in
sectors 21-30:
Summary
 With the standard load, at a 3-ampere setting (half of maximum
output), and for frequencies, f, between 240 Hz > f > 0.5 Hz,
the SCOR-6 corrector power supplies regulate at an rms of
3×10-5 with respect to their full 6-ampere output scale.
 A significant component of this is a 60-Hz ripple.
 This regulation improves at a zero-current setting to 0.4×10-5
and becomes worse at the full 6-ampere setting, to 4×10-5.
 This is ~10-times better than was originally expected.
 It means that these correctors can be used for the LCLS,
probably in sectors 22-30, but must be upgraded in sector 21,
and possibly sector 22 (work in progress).