How to redirect link page to new tab using onclick event not href attribute?

Hi,
i created dynamically  html button server side using c# code and  onclick() event , i am  calling server side method() on page post-back ...in server side redirect method some parameters are used ...

I want to redirect page in new tab and keep existing page as it is, please provide your solution  with onclick() event or server side code.

Server side dynamic html code created for link button:
fileTest.Append(" <span>");
fileTest.Append("<a id=\"lnkPsBtn" + TestCatBuilder.GetCategoryById(category.CategoryId).Name + "\" name =\"lnkPsBtn" + TestCatBuilder.GetCategoryById(category.CategoryId).Name + "\"onclick=\"SearchTestData('" + TestCatBuilder.GetCategoryById(category.CategoryId).Id + "')\" > ");
                    fileTest.Append(TestCatBuilder.GetCategoryById(category.CategoryId).Name);
                    fileTest.Append("</a></span>");
 
 Script code:
<script type="text/javascript">
        function SearchTestData(someid) {
            __doPostBack("lnkPsBtn" + someid, someid);
        }
 
        // Postback
        function __doPostBack(eventTarget, eventArgument) {
            if (!theForm.onsubmit || (theForm.onsubmit() !== false)) {
                theForm.__EVENTTARGET.value = eventTarget;
                theForm.__EVENTARGUMENT.value = eventArgument;
                theForm.submit();
            }
        }
    </script>
 
 
Test.Redirect(urlParams);
 
  /// <summary>
        /// this will redirect the current HttpContext to the route based on the parameters given
        /// </summary>
        /// <param name="parameters">some parameters</param>
        public void Redirect(T parameters)
        {
            if (HttpContext.Current == null) return;
           
            HttpContext.Current.Response.RedirectToRoute(_routeName, new RouteValueDictionary(parameters));
            HttpContext.Current.ApplicationInstance.CompleteRequest();
        }