"Right."

"It is also a hot, fairly tight stream. Eventually it'll spread out into nothing, like any rocket exhaust. But suppose a ship were following you here." Brennan made pictures on the screen: two tiny ships, the second following one hundred miles behind the first. He spread a wide cone before the lead ship, converging it almost to a point behind the ship. A needle shape with the ship in it's point---the ship's protective shield---brought the incoming hydrogen into a ring shaped constriction.

"You're collecting the fuel for him. His ram field is only a hundred miles across---" Brennan drew a much narrower cone. "---and it gives him finer control over his fuel flow. It's already hot and dense. It burns better in higher-order fusion. The exhaust would be rich in beryllium."

"It's just one of the things those remaining Pak might have tried. The lead ship would be nothing but a ram; no onboard fuel, no insystem motor, no cargo. It would have to be towed up to ramscoop speed. The following ship is heaver, but gets more thrust."

"You think that's what's coming at us?"