Small sticks make higher temperature gases, better for heat transfer efficiency, but more smoke

Monitoring many fires seems to show that along with density, moisture, etc., the diameter of sticks has a large effect on both heat transfer and combustion efficiency.  

In a Rocket stove without a closing door, there is obviously a lot of cold excess air entering the fire. How do we raise Temperatures without limiting primary air?

Our observations seem to indicate that burning smaller diameter sticks results in more flame/higher temperatures. However, burning smaller diameter sticks also tends to make more smoke. For this reason, it may be that burning small sticks increases thermal efficiency but decreases combustion efficiency.

Conversely big sticks seem to burn slower making less flame, resulting in lower temperatures while making less smoke. Since flame from wood makes smoke, when the wood becomes charcoal, much less PM2.5 is emitted.

The Jet-Flame can burn 2” by 2” sticks and testing shows that PM2.5 gets lower with bigger diameter sticks. The jets of air make the made charcoal very hot and even big sticks stay lit. In a normal Rocket stove without a Jet-Flame, especially with wet wood, only smaller sticks will keep burning. 

The goal is to create as-hot-as-possible gases flowing next to the heat exchanger (pot) while controlling emissions. The size of the sticks does seem to have a significant influence on thermal and combustion efficiency.