I want open popup new window in datatable mrender. but Running my code appear new tab is not new window.. How to fix my code?

in thin my code

 if (o.pay_coper_type == "test" ) {
 return '<form action="../test/test.php" method="post" target="popup" onsubmit="window.open("../test/test.php", "popup", "width=500, height=500"><input type="hidden" name="p_index" value="' + o.p_index + '" ><input type="submit"  value="print" ></form>'; }