the direction of the inner Galaxy.

Core-collapse supernovae in associations of massive OB stars are certain to produce a fraction of galactic CRs, as demonstrated by isotopic measurements by the [*Advanced Composition Explorer*]{} [see e.g., @binns_SB07]. Active star-forming regions may comprise extended associations of massive young stars like Cyg OB2 [see e.g., @cygOB2_mnras14], as well as compact dense clusters of young massive stars like Westerlund 1 (). These extended and compact cluster types are distinct in both spatial and temporal scales [e.g., @clust_assoc_mnras11]. Both type of clusters of massive stars are expected to be efficient PeV CR accelerators in starburst and normal galaxies [see @b14 for a review].

The compact massive cluster , with an estimated age of $3.5\!-\!5$Myr, contains more than 50 post main sequence stars [e.g., @Clark_Wd1_AA05], including at least 24 Wolf-Rayet (WR) stars of both flavours (representing about 8% of the observed galactic population of WR stars) in about a parsec-scale core [e.g., @Clark_Wd1_AA05; @Wd1_WR_stars_06]. These massive stars have strong individual winds with an estimated total cluster kinetic power exceeding 10$^{38} \ergs$. In the small, dense cluster core these individual winds should combine and drive a fast cluster-scale wind by the mechanisms studied by @chev_clegg85 and @stevens03. 