I am to produce a research presentation for a class of Masters' physics students on the casimir force, going via a detailed treatment of the vacuum effects in conducting cavities, going on to explain some real phenomena and applications. What I am after is a good introductory text on quantum fields, in particular vacuum fluctuations. Most that I have been able to find are texts that deal more with particle physics rather than 'no-particle physics' that I'm looking for, with the exception of one - Cavity Quantum Electrodynamics by Paul Berman which is interesting but very specialised in its examples, and doesn't give an accessible treatment of the basic effects. I'd also like to understand more about the difference between the virtual particle and vacuum expectation value approaches, and whether they are merely philosophical in nature or whether they have significant differences in derivation. I'm intentionally posting this here since although it's technically a homework assignment, I'm not asking for help with answers.