F. Najmabadi, K. Schoenberg

A burning plasma experiment is a key step in developing fusion. The realization of fusion, however, requires scientific progress in many other plasma physics and technology areas. Examples include: steady-state advanced plasma modes with low recirculating power and high beta, steady-state operation of impurity control/particle exhaust system under prototypical particle and energy fluxes, etc. An important discriminator among various embodiments of burning plasma experiments is the flexibly to examine these scientific challenges toward development of fusion.

The charter of this subgroup is to develop quantities the technical requirements and metrics for the realizationdevelopment of fusion as an energy source and to evaluate and assess fusion development path based on the different proposed burning plasma experiments. In addition, the subgroup will explore how alternative concepts contribute to and are folded into a fusion development path.

The scope of subgroup activity is limited to MFE concepts that are at least at in the proof of principle and beyonddevelopment stage (compact stellarator, RFP, ST, and tokamak).

Work Outline

Examples include (in each case, the criteria for success is that a there is sufficient scientific basis such that a device can be built and licensed):

1. Demonstration of high-Q fusion burn,
2. Demonstration of steady-state discharges with low recirculating power and high beta,
3. Demonstration of steady-state operation of in-vessel components under prototypical heat and particle flux,
4. Development of low-activation material.
5. Development of power technologies and tritium extraction systems
6. Etc

The Subgroup will use the existing large body of research in this area to develop quantitative metrics and criteria that can be used to assess the contribution of a particular burning plasma experiment to fusion energy development.

Subgroup will consider only four cases, 1) Proceeding with Ignitor-class experiment, 2) Proceeding with FIRE-Class experiment, 3) Proceeding with ITER-class experiment, and 4) Not proceeding with any burning plasma experiments. In each case, subgroup will consider:

1. What does the base program look like?
2. What would be the complementary (companion) and/or follow-on experiments? (e.g., a separate steady state experiment, a volume neutron source, etc.?)
3. What are the advantages and disadvantages of a "multi-machine" versus "a single-step to demo" development strategy?
4. What are the advantages and disadvantages of proceeding with an international versus domestic burring plasma experiment?

4) Explore how alternative concepts contribute to and are folded into the fusion development path?

1. What are the contributions of alternative concepts to fusion development (we can borrow heavily from FESAC alternative concept panel and ICC process for this).
2. How arean alternative concepts is folded into the fusion development path when theyit reach es the performance extension phase? Does each concept have its own unique development path?
3. What are the contributions of a tokamak burning plasma experiment to development path of other concepts?

We are in the process of identifying subgroup members. In consultation with participants, a more specific list of tasks, time frames, and deliverables will be worked out.

Data on operational capabilities of proposed burning plasma experiments are needed.