Studies of axial pressure profiles and flows during gas-puff-fueled discharges in LAPD

The Large Plasma Device (LAPD) has been upgraded with a LaB6 plasma source and with gas-puff-fueling capabilities; the combination of these two has provided a range of new operational regimes. In some regimes, strong parallel flows and axial pressure gradients are observed. Axial uniformity and plasma column length are important parameters to control for many experiments conducted at LAPD. We present data on how discharge power, electron pressure gradients, and plasma flows affect the plasma column length and axial uniformity. A variety of fiber based probes in concert with spectroscopy are employed to study the distribution of neutral gas in the machine.