Low temperature plasmas are produced by photoionization of cold trapped ato
ms. Due to the threshold energy shift caused by overlapping ion fields, the
effective kinetic energy of the free electrons is increased by Delta (p)=2
C(p)/a, where a is the Wigner-Seitz radius and C(p)similar or equal to 11 i
s a universal constant. Detailed discussion is given on the self-consistent
determination of C-p, using a Debye shielded, fluctuating lattice model. T
he attainable minimum electron temperature is given by the plasma density a
lone, as T(e)similar or equal to Delta (p)/3=7/a. No Wigner crystallization
is possible in such plasmas, unless a strong confining external field is p
resent. The shift imposes a stringent cutoff on the high Rydberg state cont
ributions to the three-body recombination probabilities, and a new estimate
of the rates is presented. For a freely expanding cold plasma, an addition
al mode of adiabatic motional recombination is found to dominate plasma rel
axation.