Conveners - N. Martovetski (LLNL) and J. Minervini (MIT)

Magnet Charter

The three proposed Burning Plasma Experiment devices are all tokamaks requiring substantial magnet technology as the core of the machine. Two of the devices, namely FIRE and IGNITOR, employ pulsed, resistive TF and PF magnets which are pre-cooled to cryogenic temperatures and then adiabatically heated during the plasma pulse. The ITER device requires large (low temperature) superconducting magnets that are operated steady state for the TF coils and (long) pulsed for the PF coils. Because of the intrinsic differences in the magnet technology employed, as well as the different physics and technology missions for all three devices, it will be difficult to make a direct comparison between and among the three magnet systems. Primarily, the three magnet systems must be evaluated individually for the missions they are to accomplish, and this should form the primary basis for evaluation. That said, there are objective criteria by which they can be evaluated. The working group will draft evaluation criteria and other figures-of-merit to judge the status of the magnet systems technology for each machine, and the readiness for construction.

Below we list, as a starting point, some general evaluation criteria, list of information to be collected, preliminary task list, suggested names for Magnet Technology Sub-Group (MTSG) participants, and NSO support request. One of the first tasks of the MTSG will be to refine the criteria and tasks and make definitive assignments to evaluate the machines.

Expected performance and operating margins

Feasibility of manufacturing

Readiness for manufacturing,

e.g., need for further R&D

Capital and operating costs

Schedule for construction

Risk assessment of cost, schedule, and performance

Relevance to a DEMO

Relevance to other fusion experiments

Ability to attract and share international resources

Site issues (ease to provide power, cooling, etc)

Magnet System Design Description Document

Design and Operating Requirements, including waveforms and power demands from other systems

Design Criteria documents

Supporting analyses documentation

Magnet System capital cost

- Include power supplies, cryogenic systems

Cost of operations

- Include power costs, cryogenic costs

Any information on status of magnet component/system R&D

Design/fabrication schedules

Tabulate and evaluate machine size, energy, and power requirements

Evaluate performance

Magnetic, structural, thermal, electrical

Evaluate analysis basis

Evaluate magnet-physics performance

Current, volt-seconds, pulse length, shaping/flexibility space

Identify key technology and performance feasibility uncertainties

Evaluate manufacturing feasibility and readiness

Evaluate capital costs and operating costs

Evaluate construction schedule

Perform risk assessment of cost, schedule, and performance

Evaluate relevance to a DEMO

Evaluate ability to attract and share international resources

Write a unified report for Snowmass on Magnet Systems Evaluation

Note that, to the extent that much of this information has already been generated by the projects, there may not be a need for significant computations other then to tabulate the results in a consistent format. In some instances the MSWG may decide to independently determine some of the evaluation parameters, e.g., performance, costs, etc., but this will be decided within the MSWG. The determining factor will likely be the breadth and depth of existing material (documents, reports, memoranda, etc.) already generated by the projects.

- Nicolai Martovetsky (LLNL) and Joe Minervini (MIT) - Co-conveners

- Dick Thome (GA) - FIRE Engineering Manager and former Structures and Magnet

Systems Group Leader for ITER EDA

- John Schmidt (PPPL) - Expressed strong interest in helping evaluate magnet technology

- Joel Schultz (MIT) - presently designing FIRE Magnet and cryogenic systems, has

familiarity with IGNITOR and ITER-FEAT, and maintains several codes for evaluation of

resistive and superconducting tokamak magnet systems

- Peter Titus (MIT) - Has been a principal structural engineer and stress analyst for all 3

machines; FIRE, ITER (EDA), and IGNITOR.

• Charles Neumeyer (PPPL) — Has been responsible for power and protection of the magnet systems for many large projects (TPX, ITER, FIRE, others)

We would also like to get some input from a representative of each machine. FIRE is already covered by the people named above.

ITER - we recommend seeking help from Neil Mitchell from the ITER CTA (Coordinated Technical Activity). He is most knowledgeable of the present status of the ITER magnet systems design. In addition we will recommend a US person who will get familiar with the current status of the project and will represent the strengths and weaknesses of the ITER magnet system at the Snowmass meeting.

IGNITOR - Bruno Coppi has recommended that Peter Titus provide relevant IGNITOR input since he is most familiar with the magnets structural design and has design documentation available. Prof. Coppi will update Peter based on current engineering effort. Another point of contact for IGNITOR is Francesca Bombarda (MIT).

We can also accept help from other interested volunteers who are capable and willing to actively contribute to the evaluation tasks.