Main INDEX
Monthly INDEX
PREV
NEXT
User name Kelly
Log entry time 22:55:23 on March12,2006
Entry number 166434
keyword=position dependence of oven efficiency?
We moved from 3He to empty reference about 1805. The oven temperature then went up from about 270 to 278 C without beam (or jet cooling). Both The target and reference cell temperatures remained constant about 28.8 C. The temperature then declined slowly, with some oscillations.
At 2107 we returned to 3He cell, but it continued to cool, getting as low as 264 C before heading back up. It is now back to 269.
Hypothesis: the heating air is carried by flexible tubes and the flow is measured pretty far from the cell. If target motion changes the flow resistance, the heating efficiency could depend upon ladder position. Apparently the heating of the 3He cell is more efficient in the reference position than in the beam position.
However, we have been running the 3He cell in beam now for about an hour and the oven temperature is fairly stable at about 270 C. Nevertheless, the recent NMR was down to 38.9%.