How to add an administrator for search service application sharepoint 2013 Powershell

Hi 

I have changed my default access account for Enterprise search crawl:

$ServiceApplication | Set-SPEnterpriseSearchServiceApplication -DefaultContentAccessAccountName $searchAccount -DefaultContentAccessAccountPassword $serviceAccountPassword -Debug:$false

I need to make the account $Searchaccount (domain\spcrawl) an administrator of the search service application in Powershell.

Does anyone know the command?

br

Bjorn