I want to print the image in table cell

I want to print the image in table cell

I try to print the image using ajax function but in this line it will not
work the ajax function if i removed this ajax will work properly how can i
fix this???
tbl_row += "<td><img src="<?php echo
base_url().'images/'.'"+v.ad_id+"'.'/'.'"+v.ad_id+"'.'_thumb.jpg'; ?>"
alt="" /></td>"