  The GammeV experiment has constrained the couplings of chameleon scalar
fields to matter and photons. Here we present a detailed calculation of the
chameleon afterglow rate underlying these constraints. The dependence of GammeV
constraints on various assumptions in the calculation is studied. We discuss
GammeV--CHASE, a second-generation GammeV experiment, which will improve upon
GammeV in several major ways. Using our calculation of the chameleon afterglow
rate, we forecast model-independent constraints achievable by GammeV--CHASE. We
then apply these constraints to a variety of chameleon models, including
quartic chameleons and chameleon dark energy models. The new experiment will be
able to probe a large region of parameter space that is beyond the reach of
current tests, such as fifth force searches, constraints on the dimming of
distant astrophysical objects, and bounds on the variation of the fine
structure constant.
