Get Sub categories from a specific parent category in woocommerce

<?php
							$catTerms = get_terms('product_cat', array(
								'hide_empty' => 0, 
								'orderby' => 'ASC', 
								'child_of'=>'30' // air sampling applications
							));
							echo '<ul>';
								    foreach($catTerms as $catTerm) {
								        echo '<li>
								            <a href="'. get_term_link($catTerm) .'" >' . $catTerm->name.'</a>
								        </li>';
								    }
								    echo '</ul>'; 
						?>