  The European Workshop on Photocathodes for (particle) Accelerator
Applications (EWPAA) brings together experts in the field of photocathode based
electron sources for use in particle accelerators, with the aim of sharing
their knowledge and latest research and development progress in this crucial
field of particle accelerator science. The workshop is convened every other
year, and is thus complementary to the P3 workshop (Photocathode Physics for
Particle accelerators) run in the USA. Consequently, there is a workshop
focusing on photocathodes for particle accelerator applications convened every
year, either in Europe or the USA. The EWPAA 2022 is the 4th meeting in this
workshop series. The event was hosted by the INFN LASA Institute in Milan in
collaboration with University of Milano between September 20th and 22nd. The
programme was organised with 7 working groups, with each oral contribution
assigned to the most appropriate group. This report presents, summarised by the
work group conveners, the innovative ideas, the challenges and the main points
raised by each of the speakers.
