  We have developed two arrays of lumped element kinetic inductance detectors
working in the D-band, and optimised for the low radiative background
conditions of a satellite mission aiming at precision measurements of the
Cosmic Microwave Background (CMB). The first detector array is sensitive to the
total power of the incoming radiation to which is coupled via single-mode
waveguides and corrugated feed-horns, while the second is sensitive to the
polarisation of the radiation thanks to orthomode transducers. Here, we focus
on the total power detector array, which is suitable, for instance, for
precision measurements of unpolarised spectral distortions of the CMB, where
detecting both polarisations provides a sensitivity advantage. We describe the
optimisation of the array design, fabrication and packaging, the dark and
optical characterisation, and the performance of the black-body calibrator used
for the optical tests. We show that almost all the detectors of the array are
photon-noise limited under the radiative background of a 3.6 K black-body. This
result, combined with the weak sensitivity to cosmic rays hits demonstrated
with the OLIMPO flight, validates the idea of using lumped elements kinetic
inductance detectors for precision, space-based CMB missions.
