Download CSV file using "AJAX"

I'm trying to accomplish a fairly simple task for my website, but I"m not sure exactly how to go about it. I want the user to be viewing a table, then click a button, at which point the user can save the contents of that table as a csv file. This request can sometimes be quite complicated so I generate a progress page to alert the user.

I have most things figured out except actually generating the csv file. (I use jQuery and PHP)

the jQuery code run on click:

hmis_query_csv_export: function(query_name) {
    $.uiLock('<p>Query Loading.</p><img src="/images/loading.gif" />')
    $.get({
        url: '/php_scripts/utils/csv_export.php',
        data: {query_name: query_name},
        success: function(data) {
            $.uiUnlock();
        }
    });}

the relevant PHP:

header("Content-type: text/x-csv");
header("Content-Disposition: attachment; filename=search_results.csv");
//
//Generate csv
//
echo $csvOutput
exit();

What this does is sends the text as the PHP file, but it's doesn't generate a download. What am I doing wrong?