APS Division of Plasma Physics Meeting in Denver, Colorado (Chris)

Last week I attended the APS Division of Plasma Physics conference in Denver, CO, which was a great meeting full of learning about the state of the art in plasma physics and fusion research, updating about our progress on PFRC experiments, and discussing modeling and experimental techniques and power electronics with fellow attendees. A picture of me with my poster is shown below.

I presented a poster on modeling effects of plasma impurities (trace gases other than the main fuel, hydrogen, which tend to radiate more energy out of the plasma) on our x-ray diagnostics, which we are developing for electron temperature and density measurements. These diagnostics also give information about the electron energy distribution function (EEDF), where we can find the number of electrons at each electron energy. The EEDF hence supplies us with detailed knowledge of the plasma, including how non-equilibrium the plasma is, which can be used for verifying models and informing our other measurements. I implemented a model for line radiation from impurities and applied some more precise bremsstrahlung cross-sections and found good agreement with experiment, giving us higher confidence of our measurements even with impurities present.

There were comprehensive review talks on tokamak experiments, plasma astrophysics, and advanced plasma modeling techniques. There were also many smaller talks and poster sessions capturing the work done on plasma experiments and modeling in the vast array of sub-fields of plasma physics! It was great to also get updates on other field-reversed configuration plasmas at the conference and have fruitful discussion.

The conference venue was a good size, not too large that it would be difficult to make it to other session rooms or too small that it would feel crowded. A picture of the parts of the city surrounding the conference hotel during sunset as well as a glimpse of the surrounding mountains from the room I stayed in are shown below.

There were fire places right outside the conference center that were in good use because the first two days of the conference were pretty cold, reaching down to about 15 Fahrenheit! Since in some circumstances fire can be considered a plasma, and in general, fire has at least some charged particles, these fire pits were referenced in a few talks as an ice-breaker (no pun intended!) for discussing plasmas.

In summary, APS DPP 2023 was a great conference where I had the opportunity to:

(1) Catch up with the state of the art in plasma physics and fusion research.
(2) Present my poster on x-ray diagnostics on the PFRC and get some helpful suggestions and communicate with other groups working on x-ray diagnostics.
(3) Inquire about various groups’ power electronics requirements and setups, and also learn about application areas where people see our technologies providing a clear benefit.
(4) Learn more about plasma experimental techniques and computational/theoretical work that could potentially be applied to our fusion and power electronics work.

And with that inspiration, I’m back to work!

Technology-to-Market Summer Internship

My name is Riya Anand. I am a rising sophomore at the University of Pennsylvania studying Chemistry and pursuing minors in Environmental and Sustainability Management and Engineering Entrepreneurship at the Wharton School. This summer I worked at Princeton Satellite Systems (also doing business as Princeton Fusion Systems) as a Business and Product Development intern. 

I predominantly worked on two projects during my time at PFS: GAMOW & PFRC-3. 

GAMOW: ARPA-E GAMOW brings together Princeton Fusion Systems, Princeton University, the National Renewable Energy Laboratory (NREL), and Qorvo (formerly UnitedSiC) to develop high efficiency switching amplifiers using cascode wide bandgap (WBG) devices, employing advanced cooling technology in the form of digitally controlled boards. The Technology-to-Market (T2M) plan allows for the development of a strong understanding of a product and its surrounding market, customers, and acquisition strategies. Over the past few months, I worked on the third revision of the GAMOW T2M plan. Specifically, I worked to insert various elements to improve the strength and effectiveness of the plan to the reader. 

In order to do this, I conducted market analysis (using a TAM/SAM/SOM framework for GAMOW’s primary, secondary, & tertiary markets) and cost analysis (using both a “bottom-up” and cost-benefit framework). In conducting the analyses, I was able to meet with leaders at PFS’s collaborating companies including the Head of Marketing at Qorvo, a company that specializes in creating cascodes, to collect metrics and strategies. 

I followed up my market research with competitive analysis where I analyzed areas such as technology of focus, products, financial resources/market share, marketing strategies, future plans and growth, etc. for various competitive startups and companies. This allowed me to pinpoint areas PFS’s strengths and use it to compose a value proposition.

Figure showing the growing power electronics market for GaN, a WBG semiconductor. Source: Semiconductor Today.

Additionally, I worked to organize all of the end-user organizations that PFS has come in contact with at previous summits, conferences, etc. to ensure room for effective communication and to serve as a reminder for the needs of clientele as the GAMOW technology develops.

Finally, after meeting with some potential investors for the GAMOW technology, I put down a framework for the EBITDA margin (earnings before interest, taxes, and amortization, a measure of company profitability), valuation at exit, & return on investment that would allow for derivation of numbers that could be presented to investors, collaborators, clients, etc. and helped in creating a GAMOW Product Roadmap document and pitch deck that simplified descriptions of each of GAMOW’s products, down to images and definitions of each component, both essential for strong understanding of the technology. 

Apart from adding this information to the T2M plan, itself, I created a business/marketing slide with T2M information (including goals, target market, assessment of competitiveness, assessment of market, and a value proposition) that was used as PSS’s lead slide at the ARPA-E 2023 Energy Summit. I compiled all of the above information and other highlights within the plan into an Executive Summary of the technology that now leads the T2M report. 

PFRC: The Princeton Field Reversed Configuration (PFRC) device is a nuclear fusion reactor which provides a revolutionary approach to fusion power generation. The reactor is small and clean and can be used in diverse applications, from submarines to urban environments to space propulsion. A model of the PFRC is shown below. Under this project, I attended the 5th Annual Department of Defense Power and Energy Conference outside Washington D.C. where I heard from renowned figures such as Major General David Maxwell and was able to speak to and learn from figures such as Honorable Sharon Burke and numerous representatives from Guernsey, Ammentum, and NextEra Energy about PFRC technology and applications. 

Prior to the conference, I had been attending weekly Plasma Physics lectures under Professor Samuel Cohen at the Princeton Plasma Physics Laboratory (a national Department of Energy laboratory) and using the information I learned here to create T2M and general marketing slides, later accessible by all we spoke to at the conference. The slides included an extensive value proposition (in terms of military, space propulsion, civil terrestrial), market standing, manufacturing lead, product roadmap, end-user understanding, competitive advantage and analysis of the general industry). All of the contacts and information accumulated in this conference were compiled into a multipage summarizing document. 

Via my conversations at the Summit, I was able to set up meetings with potential collaborators/clients and PFS. One of these meetings in particular experienced success and led to further discussion and strong possibility of collaboration once technological details are finalized. 

Overview: As a whole, PFS provided me with a space where I was able to diversify my past experiences through exposure across various industries. The integration of hands-on-experience, being able to join conversations with clients, investors, and collaborators as an intern, into academic offerings made PFS an ideal environment for me to develop skills such as problem solving, effective communication, thought leadership, and collaboration, which will give me the agility and ability to understand and move between industries. I have gained experience in fields ranging from plasma physics and aerospace engineering to entrepreneurship and operations, giving me exposure to the crossroads between STEM and business. The tight knit network within the company provided me a place where I could grow, learn, and eventually, contribute to the business development efforts of the company. I would not have been able to do this without the help of each and every person at PFS who was extremely welcoming and willing to provide 1:1 mentorship and guidance each step of the way. I am extremely appreciative of PFS for giving me the opportunity to work with them this summer. I am confident that I will apply all that I have learned here to all of my future endeavors. 

Final Titan Aircraft Paper Published in Acta Astronautica

The final version of our paper, “Nuclear Fusion Powered Titan Aircraft,” by Mr. Michael Paluszek, Ms. Annie Price, Ms. Zoe Koniaris, Dr. Christopher Galea, Ms. Stephanie Thomas, Dr. Samuel Cohen, and Ms. Rachel Stutz is now available, open access, on the Acta Astronautica website. As described in our earlier post, the paper discusses a mission to Titan using the Direct Fusion Drive on the transfer vehicle, and a Princeton Field Reversed Configuration reactor to power an aircraft, that could fly around Titan for years. The reactor allows for high-power instruments, some of which were first proposed for the NASA Jupiter Icy Moon Orbiter Mission. The paper was first presented at IAC 2022 in Paris.

Two key figures were updated from the preprint version of the paper – Figure 11 and Figure 12, showing the power flow and mass breakdown of the PFRC for the electric aircraft. The earlier figures were from a larger version of the engine. The final engine design produces 0.5 MWe and has a mass of 1006 kg. This is now consistent with the system masses presented in Table 6. Vehicle Power and Payloads.

Universe Today has published an article about our mission study, “What if Titan Dragonfly had a fusion engine?”

PSS appears on the Space Business Podcast to talk about nuclear fusion propulsion

Mike Paluszek and I appear on the newest episode of Space Business Podcast to talk about nuclear fusion propulsion, Direct Fusion Drive, and the Princeton Field-Reversed Configuration (PFRC) concept!

We had a great conversation with the host of this podcast, Rafael Roettgen, who asked us thoughtful questions. In this episode, we discuss topics such as: the future of space propulsion, the history and benefits of field-reversed configurations and how they compare with other fusion reactor concepts, mass and power budget considerations of a fusion rocket, and the road ahead for research and development to get us to a prototype for space. We additionally talk about terrestrial (on earth) applications of the PFRC concept as a globally-deployable power plant for remote areas and look forward to even more futuristic space concepts that could follow after the PFRC.

You can access this episode on podcast platforms including Apple Podcasts and Spotify as well as directly on their website. Enjoy!

Our Titan Mission Paper preprint is now online in Acta Astronautica

Our IAC paper on a fusion-powered Titan mission is now available in preprint on Acta Astronautica online, with the final version to come soon! Our mission concept utilizes two PFRC reactors: one configured as a Direct Fusion Drive rocket for the journey to Titan, and a second configured as a power source for the electric aircraft that will survey Titan. The paper includes a detailed design of the aircraft and analysis of optimal entry into the atmosphere and landing on the moon’s surface.

https://doi.org/10.1016/j.actaastro.2023.04.029

Fusion-propelled transfer vehicle shown in orbit around Titan. The transfer vehicle would serve as an orbital science platform and communications relay to Earth. The 2.4 MW fusion reactor provides 1.4 MW of thrust power and 100 kW of electric power.
Fusion-powered electric aircraft for Titan science exploration. The aircraft has six ducted fan engines. The onboard reactor provides 500 kW of electric power.

Crowdfunding for fusion development closing at the end of April

Our crowdfunding opportunity at is scheduled to close at the end of the month. We’ve raised over $100K so far to support fusion development and specifically, the PFRC-2 experiment at Princeton Plasma Physics Laboratory as we close in on our ion heating milestone. This is the last two weeks to invest in our raise on SpacedVentures!

Submarine Supplier Days 2023

I attended Submarine Supplier Days 2023 in Washington, D.C. March 7 and 8. It is an opportunity for companies contributing to building the latest attack and ballistic missile submarines to get together. The two big programs are for the Columbia Class fleet ballistic missile submarine and the Virginia Class attack submarines. Australia will be buying four of th e latter. I attended the meeting to introduce people to the potential of PFRC as a power plant for future submarines. The first day was a series of presentations on the latest submarines.

On the next day we visited the offices of our N.J. U.S. Representatives and Senators to gain their support for the submarine programs. Here is the inside of the Senate office building with its Calder sculpture.

It was fun to meet people building the submarines. One company in New Jersey has a sole source contract to weld components of the submarines. Each weld is signed by a welder so it can be traced back should a problem arise.

I learned that there are major problems with materials supply and with finding workers to build the submarines. Lead times on some materials can be 80 months. The issues of on-again/off-again production were also discussed. We all agreed, as did the Congressional and Senate staffers, that continuing resolutions were bad.

You can get our submarine brochure here.

New paper published on analyzing and mitigating pulse-pile-up artifacts in PFRC-2 plasma x-ray spectra

A new paper,Analysis and Mitigation of Pulse-Pile-Up Artifacts in Plasma
Pulse-Height X-ray Spectra
” by Taosif Ahsan and our team has been published open-access in MDPI Plasma. It describes the implementation of an algorithm, the two-photon trapezoidal uncorrelated-pulse model, to improve analysis of x-ray spectra emitted from PFRC-2 plasma. This model was developed to reduce artifacts in x-ray spectra caused by pulse pile-up, PPU (the phenomenon where x-ray photons are recorded nearly simultaneously so that only one x-ray photon is recorded with a combined energy), and diagnose the tail region to see if it is a pulse-pile-up artifact or if it has physical origins.

Four scenarios are shown to illustrate pulse pile-up. The top left plot has two trapezoidal pulses overlapping close enough so that the registered peak (energy) is the addition of the peaks of the individual pulses. The bottom right plot is a case where the individual peaks are detected and so pulse pile-up is not an issue. The top right and bottom left plots are in-between cases where there is enough overlap to result in a combined pulse with an intermediate energy recorded. This figure is described in the published paper.
More figures from the published paper showing the successful mitigation of pulse pile-up using the model derived in the paper.

Experiments on the Princeton Field-Reversed-Configuration (PFRC-2) device explore nearly pure, ca. 99%, partially ionized, warm hydrogen plasmas. For these, great interest lies in the tails of the X-ray spectrum. The tail region is important as an electron temperature in the PFRC can be estimated by fitting a Maxwellian distribution. Small tails of high-energy electrons in the energy distribution (EED), even comprising less than 1% of the plasma density, can have large effects on the resistivity, stability, and reaction rates of the plasma.

This paper is a step toward understanding how PPU affects the tail region of spectra for detector-formed trapezoidal pulses. Here we focus on relatively low count rate (≤0.1/deadtime) spectra where primarily only two-photon pile-up needs to be considered. Extension of this work to multi-photon pile-up will be necessary to develop an analytical tool to diagnose and mitigate pile-up effects in the tail regions of higher count-rate spectra.

Winter Mechanical Engineering Internship

During my time at Princeton Satellite Systems, I worked on a momentum unloading project for NASA’s Gateway, a component of the Artemis program. I designed a deployable parasol that is controlled by Canadarm using Solidworks.

Solidworks is a platform I am familiar with, but I was still able to learn new functions. My favorite part of working with Solidworks is the puzzle-like nature of assemblies. When trying to make dynamic parts you have to think about how to best add relations without over-constricting or under-constricting the part. Once I finalized my initial design I was able to attend a Zoom meeting and present it to another company.

When not working on my Gateway project, I fiddled with the 3D printer to print models of the PFRC fusion reactor.

Although I have used 3D printers several times before, this time was more of a learning process. I was an acting 3D printer technician and wrote a guide with troubleshooting tips for future employees. Due to problematic unspooling and tangled filament the printer became jammed a few times, and I was unable to do the typical loading/unloading to set the filament free. This gave me the opportunity to take apart the 3D printer and see the internal mechanisms, which in turn allowed me to unjam the printer and solve the problem. I was thrilled to see inside the 3D printer and how the parts blend together!

Through my internship I learned about the complexity of the design process and how many things you need to consider when creating a product. Conceptualizing is one step, but bringing that concept into the real world requires much more research and planning. Overall, this internship was a great opportunity that allowed me to learn how to solve several engineering problems.

PFRC Article in the Journal of Fusion Energy

Our latest paper, The Princeton Field-Reversed Configuration for Compact Nuclear Fusion Power Plants, is available in the Journal of Fusion Energy, Volume 42, Issue 1, June 2023. This paper is the first released in “The emergence of Private Fusion Enterprises” collection. A view-only version is available for free here.

Our paper gives an overview of the Princeton Field-Reversed Configuration (PFRC) fusion reactor concept and includes the status of development, the proposed path toward a reactor, and the commercialization potential of a PFRC reactor.

The Journal of Fusion Energy features papers examining the development of thermonuclear fusion as a useful power source. It serves as a journal of record for publication of research results in the field. This journal provides a forum for discussion of broader policy and planning issues that play a crucial role in energy fusion programs.