  Helium is a pivotal element in understanding multiple main sequences and
extended horizontal branches observed in some globular clusters. Here we
present a spectroscopic study of helium in the nearby globular cluster M4. We
have obtained spectra of the chromospheric He I 10830 A line in 16 red
horizontal branch, red giant branch, and asymptotic giant branch stars. Clear
He I absorption or emission is present in most of the stars. Effective
temperature is the principal parameter that correlates with 10830 A line
strength. Stars with T_eff < 4450 K do not exhibit the helium line. Red
horizontal branch stars, which are the hottest stars in our sample, all have
strong He I line absorption. A number of these stars show very broad 10830 A
lines with shortward extensions indicating outflows as high as 80-100 km/s and
the possibility of mass loss. We have also derived [Na/Fe] and [Al/Fe]
abundances to see whether these standard tracers of "second generation" cluster
stars are correlated with He I line strength. Unlike the case for our previous
study of Omega Cen, no clear correlation is observed. This may be because the
sample does not cover the full range of abundance variations found in M4, or
simply because the physical conditions in the chromosphere, rather than the
helium abundance, primarily determine the He I 10830 A line strength. A larger
sample of high-quality He I spectra of both "first" and "second" generation red
giants within a narrow range of T_eff and luminosity is needed to test for the
subtle spectroscopic variations in He I expected in M4.
