SBIR Phase I Final Technical Report for Power System for Long-Pulse Neutral Beam Injectors
- Eagle Harbor Technologies, Inc., Seattle, WA (United States)
Neutral beam injection (NBI) is used for plasma heating, current drive, and as a diagnostic tool at a variety of fusion science experiments around the United States, including at DIII-D, - NSTX, , Madison Symmetric Torus (MST), , and the Lithium Tokamak Experiment (LTX). Additionally, NBI is becoming increasingly important for smaller scale validation platforms as well as several privately funded fusion concepts that have seen a resurgence in recent years. The basic principle of neutral beam injection is to provide a neutral beam, usually consisting of hydrogen or deuterium, that can penetrate into the plasma across the confining magnetic configuration. Once inside the magnetic topology, the neutral atoms are ionized and utilized for plasma heating and/or current drive applications. The extreme example of NBI is the 50 MW auxiliary heating and current drive system envisioned for the ITER experiment. For ITER, the injectors will produce up to 1 MeV D- with total beam current of approximately 40 A with pulse lengths up to 3600 s. While the ITER NBI system is a large example, the general layout and operation of the injectors are all similar and consist of an ion source section, an accelerator section, a neutralizer section, and residual ion beam dump. Each section of the NBI system is complex and requires a careful design. Typically, NBI systems are custom designed for each experiment including all the vacuum hardware and power systems. This is especially true for the large systems including ITER as well as legacy systems found at JET , , DIII-D, and NSTX-U. Recently, NBI has been utilized at several of the smaller scale validation platform experiments. These platforms are tasked with validation and discovery of critical plasma physics and engineering issues related to the burning plasma program. In many cases the smaller experiments have utilized older generation or modified diagnostic NBI systems for current drive. Here the overall cost of the system can be prohibitive, with even the cheapest systems costing a few hundred thousand to over a million dollars to procure. The creation of new NBI systems utilizing state of the art solid-state technologies can significantly reduce overall system cost while dramatically increasing NBI capabilities. The next generation NBI power systems should include the following characteristics: • Lower overall cost • Smaller and less complex system • High degree of controllability • Fast fault (grid arc) detection with automated shutdown • Ability for fast real-time feedback and control • Scalable to higher voltages • Longer operational times up to continuous operation To address these issues Eagle Harbor Technologies, Inc. (EHT) proposed a new NBI power system in the Phase I proposal. A prototype system was then designed, built, and tested during this Phase I program. This power system successfully demonstrated all the above characteristics of the ideal next generation NBI system. The overall cost of the system was held low by using high energy density solid-state switches including both traditional IGBTs and newer SiC MOSFETs. The resultant system was housed in a 20U rack, which is a drastic decrease in size and complexity when compared to the multi-rack NBI systems of the past. The EHT system gives complete control of the full-bridge topology to the user while mitigating common fault modes of the NBI. This complete control allows additional flexibility for pre-programmed heating and/or current drive profiles, which can be tailored for specific applications. When coupled with the ability for fast real-time feedback and control, it provides the fusion science community with new capabilities not possible previously. This potentially opens the door for new research for active current drive, plasma instability mitigation as well as new diagnostic techniques. The NBI power system developed during the Phase I program was capable of producing beam energies up to 15 kV with currents up to 40 A. The output parameters are scalable to higher voltages and current by manipulating circuit components and to longer operational times by adding thermal management to the key components.
- Research Organization:
- Eagle Harbor Technologies, Inc., Seattle, WA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Fusion Energy Sciences (FES)
- DOE Contract Number:
- SC0017792
- OSTI ID:
- 1429269
- Type / Phase:
- SBIR (Phase I)
- Report Number(s):
- DOE-EHT-2018-1
- Country of Publication:
- United States
- Language:
- English
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