def galprop_ringkey(self, **kwargs):
        """ return the sourcekey for galprop input maps : specifies the component and ring
        """
        kwargs_copy = self.base_dict.copy()
        kwargs_copy.update(**kwargs)
        self._replace_none(kwargs_copy)        
        try:
            return NameFactory.galprop_ringkey_format.format(**kwargs_copy)
        except KeyError:
            return None