diff --git a/crpptbx/TCV/gdat_tcv.m b/crpptbx/TCV/gdat_tcv.m
index 83c950a1f4a3688ad2f3829bf16f74c36700226b..b6559aa7a3ec03ddd50a31ebf8b380e1c5633fb2 100644
--- a/crpptbx/TCV/gdat_tcv.m
+++ b/crpptbx/TCV/gdat_tcv.m
@@ -808,6 +808,13 @@ elseif strcmp(mapping_for_tcv.method,'switchcase')
     gdat_data.request_description = ['data=psi, x=(R,Z), eqdsk contains eqdsk structure with which ' ...
                     'plot_eqdsk, write_eqdsk, read_eqdsk can be used'];
     
+    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+   case {'halpha'}
+    channels = -1;
+    if isfield(gdat_data.gdat_params,'channels') && ~isempty(gdat_data.gdat_params.channels)
+      channels = gdat_data.gdat_params.channels;
+    end
+
     %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    case {'mhd'}
     % load n=1, 2 and 3 Bdot from magnetic measurements