  In the first part of this paper we prove that the mapping class subgroups
generated by the $D$-th powers of Dehn twists (with $D\geq 2$) along a sparse
collection of simple closed curves on an orientable surface are right angled
Artin groups. The second part is devoted to power quotients, i.e. quotients by
the normal subgroup generated by the $D$-th powers of all elements of the
mapping class groups. We show first that for infinitely many $D$ the power
quotient groups are non-trivial. On the other hand, if $4g+2$ does not divide
$D$ then the associated power quotient of the mapping class group of the genus
$g\geq 3$ closed surface is trivial. Eventually, an elementary argument shows
that in genus 2 there are infinitely many power quotients which are infinite
torsion groups.
