@MarkAdler's comment led me to ask Why would a slow spiral from a C3 of zero take about 2.4 times as much ΔV as an impulsive maneuver? which resulted in this tidy and efficient @MarkAdler answer which points to another thoughtful answer about slowly spiraling out from a circular orbit to escape in the limit of very weak prograde propulsion, which (at first counterintuitively) slows you down while raising your orbit.
Always aligned with the velocity vector. That is the most efficient use of the thrust in order to increase the specific energy. The final γ is 31°†.
Question: In this context, what is the angle γ? How is it defined?
† The phenomenon is correct but 31° was a typo and should be about 39.2° instead.