  Since the undulator wall is being bombarded by photon produced in the ILC
helical undulator, masks were installed inside the undulator to protect the
superconducting undulator as well as the vacuum. The photon energy spectrum was
used to calculate the incident power. HUSR software was used to simulate the
photon energy spectrum per meter inside the undulator. The influence of adding
masks inside the undulator on the photon polarisation and energy spectrum was
also studied.
