On the mechanisms governing gas penetration into a tokamak plasma during a massive gas injection

A new 1D radial fluid code, IMAGINE, is used to simulate the penetration of gas into a tokamak plasma during a massive gas injection (MGI). The main result is that the gas is in general strongly braked as it reaches the plasma, due to mechanisms related to charge exchange and (to a smaller extent) recombination. As a result, only a fraction of the gas penetrates into the plasma. Also, a shock wave is created in the gas which propagates away from the plasma, braking and compressing the incoming gas. Simulation results are quantitatively consistent, at least in terms of orders of magnitude, with experimental data for a D 2 MGI into a JET Ohmic plasma. Simulations of MGI into the background plasma surrounding a runaway electron beam show that if the background electron density is too high, the gas may not penetrate, suggesting a possible explanation for the recent results of Reux et al in JET (2015 Nucl. Fusion 55 093013)

Sector 1-LTR-RTL-Sector 2 treaty

We have determined the location of the linac and damping ring interface. This treaty point serves as a pivot about which the optics for sector one, the Linac-To-Ring lines, Ring-To-Linac lines, and sector two have been designed. The treaty location is at Z = 98.7532 m from the beginning of the SLC linac sector one. Our choices of location and beam parameters are consistent with the verbal charter of Ecklund, Fieguth, and others

Application of online modeling to the operation of SLC

Online computer models of first order beam optics have been developed for the commissioning, control and operation of the entire SLC including Damping Rings, Linac, Positron Return Line and Collider Arcs. A generalized online environment utilizing these models provides the capability for interactive selection of a desired optics configuration and for the study of its properties. Automated procedures have been developed which calculate and load beamline component set-points and which can scale magnet strengths to achieve desired beam properties for any Linac energy profile. Graphic displays facilitate comparison of design, desired and actual optical characteristics of the beamlines. Measured beam properties, such as beam emittance and dispersion, can be incorporated interactively into the models and used for beamline matching and optimization of injection and extraction efficiencies and beam transmission. The online optics modeling facility also serves as the foundation for many model-driven applications such as autosteering, calculation of beam launch parameters, emittance measurement and dispersion correction

Initial results from model independent analysis of the KEK ATF

Model Independent Analysis (MIA) has shown the potential to be a useful tool for diagnostics and optics verification. The Accelerator Test Facility (ATF) prototype damping ring at KEK has a diagnostic system with the ability to collect data allowing the application of MIA for analysis of the injection stability, and the storage ring optics and diagnostics. Understanding of all these issues will be important for improving the operational performance of a damping ring. We report here the results of a first attempt to apply MIA to the ATF

Models and simulations

On-line mathematical models have been used successfully for computer controlled operation of SPEAR and PEP. The same model control concept is being implemented for the operation of the LINAC and for the Damping Ring, which will be part of the Stanford Linear Collider (SLC). The purpose of this paper is to describe the general relationships between models, simulations and the control system for any machine at SLAC. The work we have done on the development of the empirical model for the Damping Ring will be presented as an example