||Using superconducting cavities proved
to be a reliable and efficient way to provide RF power to high-current,
high-energy beams. Significant operating experience was
accumulated in recent years in running superconducting cavities in
electron-positron colliders CESR and KEKB. Recent results are
reviewed. Successful operation of these machines as well as of
accelerators of an older generation like LEP, TRISTAN and HERA made
superconducting RF the technology of choice for many other high-current
colliders (BEPCII, LHC) and light sources (CLS, DIAMOND, SOLEIL, TLS).
A full set of superconducting cavities for LHC has been already
manufactured and tested. The first cryomodule for SOLEIL was
fabricated, tested on a test stand at CERN and recently was subjected
to a beam test at ESRF. The first CLS cryomodule has been
commissioned without beam. Results of those tests are discussed.
Another trend in recent years is to use beam-driven (passive)
superconducting cavities for bunch length manipulation. Harmonic
cavities are commonly used for this purpose. In the collider mode
of operation bunch shortening enhances luminosity. Recent
experimental results with fundamental RF harmonic cavities at CESR-c
are presented. In the light source mode of operation bunch
lengthening improves beam lifetime and raises coupled-bunch instability
thresholds as it is shown by experience with third-harmonic cavities at
SLS and ELETTRA. BESSY-II plans to use a third-harmonic passive
superconducting cavity for bunch lengthening as well.