  We describe the concepts and technical realization of the high-resolution
soft-X-ray beamline ADRESS operating in the energy range from 300 to 1600 eV
and intended for Resonant Inelastic X-ray Scattering (RIXS) and Angle-Resolved
Photoelectron Spectroscopy (ARPES). The photon source is an undulator of novel
fixed-gap design where longitudinal movement of permanent magnetic arrays
controls not only the light polarization (including circular and 0-180 deg
rotatable linear polarizations) but also the energy without changing the gap.
The beamline optics is based on the well-established scheme of plane grating
monochromator (PGM) operating in collimated light. The ultimate resolving power
E/dE is above 33000 at 1 keV photon energy. The choice of blazed vs lamellar
gratings and optimization of their profile parameters is described. Due to
glancing angles on the mirrors as well as optimized groove densities and
profiles of the gratings, high photon flux is achieved up to 1.0e13
photons/s/0.01%BW at 1 keV. Ellipsoidal refocusing optics used for the RIXS
endstation demagnifies the vertical spot size down to 4 um, which allows
slitless operation and thus maximal transmission of the high-resolution RIXS
spectrometer delivering E/dE better than 11000 at 1 keV photon energy. Apart
from the beamline optics, we give an overview of the control system, describe
diagnostics and software tools, and discuss strategies used for the optical
alignment. An introduction to the concepts and instrumental realization of the
ARPES and RIXS endstations is given.
