Field emission methods, models and applications
Y. Feng (UCB-NE)

Part I : A model for effective field enhancement for Fowler-Nordheim
field emission.

In computational models, it is impractical to determine the
time-dependent local surface field each time step on a microscopic
space scale. So we introduce effective beta to allow us to study the
emission properties at a macroscopic scale. The model allows reduction
of dimensionality as well as the ability to include subgrid effects.

Part II :Transition from Fowler-Norheim field emission to space charge
limited current density.

This work analyzes the transition of the transmitted current density
from the Fowler-Nordheim law to the Child's law space charge limit
using a one-dimensional PIC code. Also studied is the response of the
emission model to strong electric fields near the transition point.

Part III : A second-order accurate scheme for time-centered injection
of relativistic particles

Keith Cartwright's 2000 JCP paper developed the second-order
time-centering method for non-relativistic case. We set up all the 5
methods analyzed in Cartwright's paper to our PIC code (OOPD1) and
tested it as the paper did. We further developed the relativistic
methods by extending the 5 non-relativistic methods. Also, the
accuracy of the relativistic methods is determined and compared to
some simple test cases.