  Recent observations by CREAM and ATIC-2 experiments suggest that (1) the
spectrum of cosmic ray (CR) helium is harder than that of CR proton below the
knee 10^15 eV and (2) all CR spectra become hard at > 10^11 eV/n. We propose a
new picture that higher energy CRs are generated in more helium-rich region to
explain the hardening (1) without introducing different sources for CR helium.
The helium to proton ratio at ~100 TeV exceeds the Big Bang abundance Y=0.25 by
several times, and the different spectrum is not reproduced within the
diffusive shock acceleration theory. We argue that CRs are produced in the
chemically enriched region, such as a superbubble, and the outward-decreasing
abundance naturally leads to the hard spectrum of CR helium if CRs escape from
the supernova remnant (SNR) shock in an energy-dependent way. We provide a
simple analytical spectrum that also fits well the hardening (2) because of the
decreasing Mach number in the hot superbubble with ~ 10^6 K. Our model predicts
hard and concave spectra for heavier CR elements.
