As Inertial Fusion Energy (IFE) has oved from an academic to a privately funded effort it has become possible to re-examine all the assumptions about ICF research. During this re examination, paradigms about how these facilities are built and designed should be broken so that new IFE power plants may be built. Inertial Fusion Energy breaks into two parts: drivers and targets; of these, mass manufactured targets are the larger technical risk because of under investment by the National Nuclear Security Administration. ICF has spent decades testing different driver technologies since the fields’ inception. These include hyper-velocity projectiles, particle beams, solid-state and excimer laser systems. Private investment that has gone into hyper-velocity projectiles devices has only produced less than 100 thermonuclear neutrons [4]. Though more elaborate and expensive machines may be more successful, this low yield does not bode well for the hypervelocity approach. Particle beams (electrons, light ions, and heavy ions) were studied at Sandia from 1970 to the 1980’s and these encountered challenges with control over beam focus, beam energy, target compression and beam density [5]. Neither of these drivers have been able to generate the fusion yields that laser systems have demonstrated [6]. All of this leads to a technical down selection to a laser driver; but within that design space there are still multiple compression approaches, laser systems and target design challenges that must be overcome. Ignition is still a challenging process to model, control and understand. This response will cover issues with drivers, target manufacturing, laser diodes and IFE startup approaches.

To operate a fusion device within the United States a company currently needs consent from their state regulator. The regulations around fusion devices are based on particle accelerators that make or use radioactive materials; but these rules are likely to change. The NRC committed to regulating fusion in 2009 but only started to have conversations with industry about new regulations in 2020. A fusion power plant would be different enough from conventional nuclear plant in that the industry would be best served by having its’ own regulations. Moreover, if the NRC acted too quickly it would hinder the development of this emerging industry. Recently, Senators Tom Carper and Shelley Capito sent a letter to the NRC indicating the Senates’ willingness to take on fusion regulations directly. In this paper, NLF walks through potential accidents of fusion power plants and possible ways that industry could model these events. The paper also discusses the structure of the NRC and looks at the current regulatory hurdles that the advanced fission industry must overcome to operate in the United States.

Current propulsion technology is insufficient for commercially viable travel beyond Earths’ geosynchronous orbit. This region is known as cislunar space, and it is roughly 2,700 larger than our current region of developed space. Fusion propulsion enables rapid trip times with larger payloads, navigation of both stable and unstable orbits, and multiple service missions such as orbit transfers, repair and debris remediation without refueling. It will be required for missions such as planetary defense, colonizing Mars, mining asteroids, rapid exploration of the solar system, and protecting access to space. This paper recommends an acceleration in the development of fusion rocket candidates with a low Technology Readiness Level and then a technical down selection to more promising candidates with a fusion gain of unity.

Climate change is a global challenge, and the Biden Administration has tasked federal agencies including NASA to fund technical solutions. Fusion power is a high-profile, zero-carbon energy source that addresses those priorities. Fusion also has natural extensions into NASA mission needs because it can be used in rocket technologies. Fusion development has also changed dramatically in the past decade; the field has transitioned into a 3-billion-dollar private commercial activity. This has happened because new magnet technology has made net fusion power much more realizable. Because of this the four fields of fusion, fusion rockets, advanced magnets, and superconducting wire will be linked together over the next decade. Table 1 summarizes each field and gives recommendations for NASA involvement. Fusion rocketry is identified in Section B as a low TRL technology that should be funded. Superconducting wire and ultra-high field magnets are listed in Section A as being at a tipping point. In magnets, several innovations are ready now in academic settings. These could be brought to market via NASA funding. In superconducting wire, a Russian company has realized a breakthrough fabrication process that America must also duplicate if the US is to stay competitive. Of these four related fields, the fabrication of cheap superconducting wire would create the most jobs and have the biggest economic impact. Cheap superconducting wire can impact a dozen green energy markets from wind turbines, storage solutions, electric vehicles, and ultimately fusion reactors. This paper will lay out specific targeted investments that NASA could make to push fusion rockets and the corresponding magnets over this tipping point.

Topic A in this RFI is for information on non-thermonuclear approaches for fusion that scale to net energy, approaches that use advanced fuels, or for technology that enables either topic. This response will focus on all the questions in topic A. It will show how new high field (20-40 T) high temperature superconducting (HTS) magnets can help both plasma-based thermonuclear and non-thermonuclear approaches using advanced fuels. It will argue that ARPA-E should apply its resources on a program to develop high field, continuously operating magnets for fusion. The goal of the next ARPA-E program should be to leverage the existing US network of high temperature superconducting magnet organizations to focus on the unique requirements of fusion devices. This research will lay the technical foundation for transitioning high-field magnets into various fusion approaches, including, but not limited to the Dynomak, Spheromak, Mirror, Stellarator, and Princeton Field Reversed Configuration. This research will also help to maintain US R&D leadership against increasing international competition.

The performance of fusion devices typically scales with B3 and B4. For decades, fusion machine performance has been limited by the modest fields attainable by traditional Low Temperature Superconductors (LTS). Fusion devices can now benefit from higher field magnets, enabled by High Temperature Superconducting (HTS) materials. The MagLab has delivered the world’s only 32 T magnet (32 mm cold bore) HTS and LTS hybrid magnet. We propose extending this technology to a larger bore, higher field systems suitable for a fusion device. We see the next development step as a novel ~18 T, ~24 cm cold bore system using the next generation pancake winding technique. This new approach to winding allows for current densities that are 1.4 time higher than those of the 32 T magnet. This will be accomplished by increasing the ratio of operational to critical current inside the coil. This will reduce the energy margin of the coil, resulting in faster response of the quench protection system. It will do this, while keeping the peak temperature after quench lower than that of the 32 T magnet. In addition, we will use multiple Rare-Earth Barium Copper Oxide (REBCO) tapes wound into insulated turns (MTI) to allow for higher current operation. When compared to single strand designs, this improves quench protection and reduces the overall sensitivity to point defects in the tape. The MTI coil will provide a significant improvement in the stable and reliable maximum magnetic field strength. The coil will provide a high performance magnet for use in fusion devices.