Designing and developing the 1.7 to 2.I-MJ Power' Conditioning System (PCS), that will power the flashlamps of the main and power amplifiers for the National Ignition Facility (NIF) lasers, is one of several responsibilities assumed by Sandia National Labs (SNL) in support of the NIF Project.Maxwell Physics International has been a partner in this process. The NIF is currently being constructed at Lawrence Livermore National Labs (LLNL). The test facility that has evolved over the last three years to satis& the project requirements is called FANTM, for the Fkst Ardcle NE Test Module. It was built at SNL and operated for about 17,000 shots to demonstrate component performance expectations over the lifetime of ND?. A few modules similar to the one shown in Fig. 1 will be used initially in the amplifier test phase of the project. The final full NIF system will require at least 192 of them in four capacitor bays. This paper briefly summarizes the final design of the FANTM facility and compares its performance with the predictions of circuit simulations for both normal operation and fault-mode response. Applying both the measured and modeled power pulse waveforms as input to a physics-based, semi-empirical amplifier gain code indicates that the 20-capacitor PCS can satisfy the NIF requirement for an average gain coefficient of 5.00 %/cm and can exceed 5.20 Ye/cmwith 24 capacitors. I. FANTM PULSED POWER DESIGN 'The FANTM bank consists of 20 (24 max) 86-kJ, nominally 300+.F capacitors that &e operated in parallel near 24 kV. Each capacitor (C in Fig. 1) is isolated from ' the rest of the bank by a current-limiting damping element (D), which is a 25-mQ, 9-pH resistive coil. They connect to a single bus (B) that feeds the gas switch (S). The single ST300A air-insulated switch transfers over 500-kA peak current in a 300+.s FWHM critically damped pulse from the bank into 20 parallel output lines. Each of these

This paper describes a set of analyses and tests perfonned to evaluate approaches to provide a safe and robust grounding approach for the main Power Conditioning System (PCS) in the National Ignition Facility (NIF) facility presently under construction at the Lawrence Livermore National Laboratory (LLNL). The Power Conditioning System consists of up to 192 capacitor bank modules, each storing 2.2 MJ and capable of producing a peak current over 500 kA. The grounding system must minimize touch potentials associated with operation of the Power Conditioning System. In the event of severe faults, the system must assure that the energy delivered to a person through contact with "grounded" structures is very low. Based on computer modeling and low-voltage, lowcurrent tests, we have concluded that the most effective approach is a set of metal enclosures around the output cables (effectively heavy-wall closed cable trays) extending from the capacitor bank modules to their flashlamp loads. This paper will discuss the safety standards identified for this application, the approach to meeting the standards, and the predicted performance of the safety system.

Designing and developing the 1.7 to 2.1-MJ Power Conditioning System (PCS) that powers the flashlamps for the National Ignition Facility (NIF), currently being constructed at Lawrence Livermore National Labs (LLNL), is one of several responsibilities assumed by Sandia National Labs (SNL) in support of the NIF Project. The test facility that has evolved over the last three years to satisfy the project requirements is called FANTM. It was built at SNL and has operated for about 17,000 shots to demonstrate component performance expectations over the lifetime of NIF. A few modules similar to the one shown in Fig. 1 will be used initially in the amplifier test phase of the project. The final full NIF system will require 192 of them (48 in each of four capacitor bays).This paper briefly summarizes the final design of the FANTM facility and compares its performance with the predictions of circuit simulations for both normal operation and fault-mode response. Applying both the measured and modeled power pulse waveforms as input to a physics-based, semi-empirical amplifier gain code indicates that the 20-capacitor PCS can satisfy the NIF requirement for an average gain coefficient of 5.00 %/an and can exceed 5.20 %/cm with 24 capacitors. FANTM PULSED POWER DESIGNThe FANTM bank consists of 20 (24 max) 86-kJ, nominally 300-pF capacitors that are operated in parallel near 24 kV. Each capacitor is isolated &om the rest of the bank by the current-limiting damping elements, which are 25-mQ,9-pH resistive coils. They connect to a single bus that feeds the gas switch. The single ST300A airinsulated switch transfers over 500-kA peak current in a 300-ps FWHM critically damped pulse from the bank into 20 parallel output lines. Each of these lines is composed of a matched ballast inductor, an RG 220A.J coaxial cable, which is 47.6-m long, and either a dummy resistive load or a pair of series-connected flashlamps. The full NIF will also include modules with a range of output cable lengths from 20 to 55 m, due to the different locations of the PCS modules with respect to the laser amplifiers. The main bank module has a weight of approximately 7 metric tons, a footprint of about 1.52 by 3.35 m, and a total height of about 3.11 m. A flashlamp pre-ionization pulse from a smaller 50-W PreIonizationLamp Check (PILC) parallel bank precedes the main pulse by a few hundred microseconds. The following subsections describe the PCS components in more detail. A. High Energy Density CapacitorsThe metallized-dielectric, self-healing capacitors which are supplied by several sources are installed in two facing columns, or racks, each three capacitors wide and four high. The opening in the frame for each capacitor is 50.8 x 50.8 x 101.6 cm, sufficient to allow about 5-cm

Abstract_-+ f=+zrdflà numerical model, EIGOL, has been developed to calculate the loss rate of neutral beam ions (-J ST \ from NSTX and the resultant power density on the plasma facing components. This model follows the fill gyro-orbit of the beam ions, which can be a significant fraction of the minor radius. It also includes the three-dimensional structure of the plasma facing components inside NSTX. Beam ion losses from two plasma conditions have been compared: fl=23%, qO=0.8, and~=40'Zo, qO=2.6.Global losses are computed to be 4% and 19%, respectively, and the power density on the rf antenna is near the maximum tolerable levels in the latter case.

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