diff --git a/matlab/TCV/tcv_requests_mapping.m b/matlab/TCV/tcv_requests_mapping.m
index 7e19352720d39a4f5eb9b971abdaeabc46e833f0..6c91786ca18314ecf6dc89a40cfde6d041ad5e87 100644
--- a/matlab/TCV/tcv_requests_mapping.m
+++ b/matlab/TCV/tcv_requests_mapping.m
@@ -442,6 +442,17 @@ switch lower(data_request)
   mapping.timedim = 1;
   mapping.gdat_timedim = 2;
   mapping.method = 'switchcase';
+ case 'tau_r'
+  mapping.timedim = 1;
+  mapping.gdat_timedim = 1;
+  mapping.method = 'expression';
+  mapping.expression = ['params_eff = gdat_data.gdat_params;params_eff.data_request=''a_minor''; ' ...
+                    'gdat_tmp=gdat_tcv([],params_eff); ' ...
+                    'params_eff = gdat_data.gdat_params;params_eff.data_request=''\results::ibs:signeo''; ' ...
+                    'aa=gdat_tcv([],params_eff);ix=iround_os(aa.x,0.4); ' ...
+                    'bb=interpos(aa.t,aa.data(ix,:),gdat_tmp.t,-100);' ...
+                    'gdat_tmp.data = 4e-7*pi.*gdat_tmp.data.^2.*bb./1.22; gdat_tmp.label=''\tau_R'';gdat_tmp.gdat_request=''tau_r'';' ...
+                    'gdat_tmp.units=''s'';gdat_tmp.help=''tauR=mu0 a^2 / 1.22 etaneo(rhopol=0.4)'''];
  case 'te'
   mapping.timedim = 2;
   mapping.label = 'Te';