Accelerator Modeling. We will complete the development of a capability for simulating the time-dependent fluid dynamics of gas jets and plasma formation as arises in the design of laser-plasma accelerators [15]. Laser ionization of the gas plume serves as the plasma source in these accelerators, and optimal tailoring of the plasma density through judicious jet design and these use of channel-forming lasers is necessary to enhance accelerator performance [31]. The code will use the AMR embedded boundary tools for solving the compressible Navier-Stokes equations for flow in the injector. refinement. The results of these simulations will be benchmarked against experiments carried out at LBNL.
Magnetic Fusion. In FY02, we will complete the development of an embedded-boundary MHD code for tokomak modeling, based on the embedded boundary software tools for cylindrical geometry developed in FY02. This code will have the same physics models as the rectangular-domain code developed in FY01: a fluid representation of the plasma, an unsplit Godunov method for the hyperbolic terms, and a semi-implicit representation of nonideal effects such as resistivity and viscosity. We will also undertake to develop suitable AMR discretizations of the Hall effect terms in nonideal MHD. These terms present particular difficulties, in that they give rise to a nonlinear second-order operator that is dispersive, rather than dissipative.
Combustion. In FY03, we plan to expand our collaborations with researchers at the University of Heidelberg and the Technical University of Denmark to include the researchers in the High Temperature Gasdynamic Laboratory at Stanford University. The group is planning a series of experiments on bunsen-type high pressure premixed flames. The primary difficulty in simulating high-pressure flames is twofold: the lack of thermodynamic, transport and chemistry data, and the numerical resolution requirements due to thinner flame fronts. The application is ideal from an adaptive grid standpoint, and will provide simulationmodeling experience required for our FY04 plans. The experiments will be geared at obtaining NO production behavior under various operating scenarios, employing techniques very similar to those used in the ammonia-seeded diffusion flames detailed above.
We will continue our investigations of combustion chemistry interactions with fuel-stream turbulence. As computational hardware capabilities increase, along with the performance of our simulation technology, we will begin to model NO pollutant formation processes in turbulent flames. In particular, we will begin characterize how features such as stretch and flame curvature affect NO production. These studies will be carried out using a configuration similar to that used in the turbulence-chemistry interaction investigations detailed for FY02.