Each wave requires a certain number of kills to reach. The easiest way to get to wave ten safely is to start a game in "one-life" mode, and play pacifist until the screen is nearly full. Since you've made no kills, only the slow moving, non-tracking orange circles will spawn. When there's too much to handle, release a blast with
or
to get hundreds of kills and skip straight to wave 7-9. Kill the remaining orange circles to get to wave ten with little risk.
Or, just play normally in one-life mode, you will certainly get this on the way to 850,000 points in that mode.