Summary of recent TRANSP runs

Here is the summary of recent PTRANSP runs

Case # Description Comments
141716H09/10 ExB flow shear is enabled for W19 and disabled for DRIBM
141716H11/12 ExB flow shear is disabled for W19 and DRIBM
141716H13/14 MMM95 is used instead of MMM7.1 relatively small changes in diffusivities
141716H17/18 MMM7.1 with ExB flow shear effect for DRIBM ITG/TEM diffusivities goes almost to zero with current levels ExB flow shear effects
141716H19/20 ExB flow shear factor is reduced from 1 to 0.5 for W19 and DRIBM see comment below
141716H21/22 flow shear factor is increased from 0.5 to 0.75
141716H23/24 k_yrho in DRIBM is increased from 0.2 to 2 see comments below
141716H25/26 flow shear factor is reduced from 0.75 to 0.5 for W19 and to 0.1 for DRIBM see comments below

There are various definitions of omega_{rm Etimes B} including the Hahm-Burrell and Waltz-Miller definitions. The flow shear rates computed using different definitions are often varied by a factor of 2 or more. The effect of ExB flow shear on particular modes in tokamak even is less certain and requires detailed studies. I plan to vary the ExB flow shear factor from 0.1 to 1 in my simulations depending on the scales of particular modes. In particular, I reduce the ExB flow shear factor to 0.1, when I change k_yrho from 0.2 to 2, but I keet the ExB flow shear factor 0.5 for W19 that has k_yrho=0.316 in the PTRANSP simulations 141716H25 and 141716H26.

Some results from my PTRANSP simulations are below.
Case 141716H19/20
Electron thermal diffusivity from Weiland model
The effect of ExB flow shear is clearly visible if these results are compared with the results from the case 141761H11/12 that does not take into account the ExB flow shear effect for W19:
Electron thermal diffusivity from Weiland model
Without the ExB flow shear, the ITG/TEM modes become more unstable at later time. Account for the ExB flow shear makes these modes more stable at the later time.
Case 141716H23/24
Electron thermal diffusivity from DRIBM model
Reduction of the characteristic scales of modes with k_yrho increased from 0.2 to 2.0 resulted in a significant level of anomalous transport in the plasma core that has not predicted with the W19 or DRIBM model with the default k_yrho parameters. The ExB flow shear factor should be probably less in these simulations because such short-scale modes should not be affected by the ExB flow shear at the same level as modes with k_yrho=0.2. I reduced the ExB flow shear factor for these modes from 0.5 to 0.1 in the next case 141716H25/26.
Case 141716H25/26
Electron thermal diffusivity from DRIBM model