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The National Spherical Torus Experiment (NSTX) at Princeton University, Princeton, NJ, is designed to assess the potential of the low-aspect-ratio spherical torus concept for magnetic plasma confinement. The plasma has been heated by up to 7 MW of neutral beam injection (NBI) at an injection energy of 100 keV and up to 6 MW of high harmonic fast wave (HHFW) at 30 MHz. NSTX has achieved [[beta].sub.T] of 32%. A variety of MHD phenomena have been observed to limit [beta]. NSTX has now begun addressing [T.sub.E] scaling, [beta] limits, and current drive issues. During the NBI heating experiments, a broad [T.sub.i] profile with [T.sub.i] up to 2 keV, [T.sub.i] > [T.sub.e] and a large toroidal rotation were observed. Transport analysis suggests that the impurity ions have diffusivities approaching neoclassical. For L-Mode plasmas, [T.sub.E] is up to two times the ITER97L H-Mode scaling and exceeds the ITER98pby2 H-Mode scaling in some cases. Transitions to H-Mode have been observed which result in an approximate doubling of [T.sub.E] after the transition in some conditions. During HHFW heating, [T.sub.e] > [T.sub.i] and [T.sub.e] up to 3.5 keV were observed. Current drive has been studied using both coaxial helicity injection with up to 390 kA of toroidal current and HHFW. HHFW has produced H-modes with significant bootstrap current fraction at low [I.sub.p], high q, and high [[beta].sub.p]. Index Terms--Fusion reactors, plasma confinement, tokamaks.

The first part of this three-part report explains the objectives of the task force and the scope of its report [1]. The first part also provides modelling guidelines for the investigation of small-signal torsional oscillations, large-signal shaft transient stresses, turbine-blade vibrations, and fast bus transfer based on the use of digital computer time-domain simulation methods. This paper provides modelling guideline for the analysis of controller interactions, harmonic interactions, and resonance phenomena. Sample lest systems and typical time-domain simulation results for each phenomenon are also provided. Keywords: Controller Interactions; Harmonic Interactions; Resonance; Modelling; Simulation.

The objective of this task force report is to provide a guideline for modelling and analyses of slow (low frequency) dynamics of electrical power systems based on the use of digital 4computer time-domain simulation methods. This report concentrates on small-signal torsional oscillations, large-signal (transient) torsional torques, turbine blade vibrations, and fast bus transfer. This report (1) briefly explains the physical nature of each phenomenon, (2) identifies those power systems components which are either contributors or are adversely affected by the phenomenon, (3) provides time-domain simulation, guidelines and (4) provides sample systems and typical time-domain simulation results. Keywords: Torsional Oscillations; Transient Torques; Turbine Blade Vibrations; Fast Bus Transfer; Modelling; Simulation.

This paper describes the study requirements to determine the effect of power system stabilizers in controlling the undamped system oscillations in interconnected power systems. This analysis is performed for the planning of excitation systems for new generators at Kemano, as well as excitation upgrade for the existing Kemano units. Available small signal stability and transient stability simulation techniques are employed. Application of trapezoidal rule in analyzing the stabilizer control scheme is also presented. A general approach to determine the optimum setting of power system stabilizers with more than one input by the root locus techniques is developed. The usefulness of the power system stabilizers in the exciters to control these oscillations is analyzed. Representative excitation system with power system stabilizers are obtained from the manufacturer. The analyses of small signal stability are conducted for both an interconnected Alcan-B.C. Hydro system and separated Alcan system. From the series of simulations, it is concluded that Kemano and B.C. Hydro generators will be subject to undamped system oscillations without the supplementary excitation control scheme at Kemano. Properly tuned stabilizers will provide sufficient damping to correct for this situation. Due to the damping capability of the stabilizers in the connected and separated Alcan system operation conditions, the adaptive control scheme can be omitted. On the other hand, untuned stabilizers can cause undesirable intraplant undamped oscillations in both connected and separated Alcan system conditions.

The communications prerequisites for achieving distributed/parallel processing of data are examined prior to the design of an interconnection network architecture. Known as the virtual bus, it is amenable to fault tolerant dynamic computing and has low communication latency. It also provides a terabit-per-second end-to-end communication bandwidth even for nonuniform traffic while upholding gigabyte-per-second transfer rates and other services.