AIAA ASCEND 2023 Papers: Liquid Rockets and Solar Parasols

We presented two papers at the 2023 AIAA ASCEND conference in Las Vegas on October 25, featuring the work of our interns William Huang and Aniesha Dyce. All GN&C analysis and simulations were performed using our Spacecraft Control Toolbox, while the parasol model was built in Fusion 360.

Thanks to the session chairs Dr. Erica Rodgers (NASA), Evan A. Bell (NASA), Melodie Yashar (ICON), and John Carsten (MEI). Our sessions included a variety of intriguing research including optical payload development, robotics from GITAI, deep space internet, a student smallsat design using a solar sail and a study of perceived spaciousness in astronaut living spaces.

Here are the abstracts for our papers:

All Liquid Fuel Space Launch System

The recent Artemis launch demonstrated the performance of the NASA Space Launch System (SLS), specifically the SLS Block 1 configuration. The launch vehicle has a central core stage with four RS-25 engines and two 5-segment solid rocket boosters (SRB). The second stage uses an RL10C-3 engine. This paper presents a conceptual design of an SLS variant using the same core vehicle but with five liquid boosters, each with a single RS-25D. This launch vehicle provides the same performance with two-thirds the launch mass. This is conceptually similar to some Shuttle variants. This paper provides an analysis and comparison of the launch vehicles’ performance and presents simulation results. In addition, it shows how the add-on boosters can be used independently as part of a high-performance two-stage to orbit (TSTO) launch vehicle. Payload and performance are given for the single boosters with a 2nd stage powered by an RL10C-3 engine. Comparison with other commercial available launch vehicles show that the TSTO vehicle proposed in this paper is a competitive in terms of the payload mass it is able to carry to low earth orbit (LEO). This launch vehicle is more complex than comparable launch vehicles. Additional work will be required to determine the cost per kilogram of the two stage launch vehicle and the cost of operating SLS with liquid boosters.

DOI: 10.2514/6.2023-4742

Gateway Momentum Unloading using a Solar Parasol

This paper describes the use of a robotic arm for momentum unloading and orbit control. A panel is attached to the end of a robotic arm. It is positioned, in angle and position, to optimize unloading. The robot arm can move about the spacecraft giving additional degrees of freedom. The panel can be stowed when necessary. The work is based partially on a technology developed by the Canadian Space Agency. The parasol can be grabbed and deployed by the robot arm whenever it is needed, to remove momentum. When it is not needed the parasol is retracted and stowed. The system can be used in high orbits for both momentum and orbit control using solar pressure. In lower orbits, it can use atmospheric drag for the same purpose. This paper focuses on its use for momentum unloading for the NASA Gateway space station. The paper includes a complete GN&C design using single gimbal CMGs with thrusters for orbit control and backup attitude control. The dynamical equations are derived and simulation results are presented for all modes of operation. This includes an optimal attitude profile for minimizing solar and gravity gradient torques over the Gateway orbit.

DOI: 10.2514/6.2023-4781
CAD model of Gateway with a solar parasol in orbit around with moon.
Gateway with Notional Solar Parasol

It was great to be part of the ASCEND conference and share our work!

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!

APS-DPP Conference held in Denver, Colorado (Sangeeta)

It was great to attend the APS-Division of Plasma Physics meeting this year held in Denver, CO. I have an opportunity to present my work with an oral presentation on ” Detection and Analysis of Low Energy X-ray emission from PFRC-2″ and also presented a poster titled ” Laboratory study of the PFRC-2’s initial plasma densification stages” along with Eugene Evans. More details about our work on densification stages can be found in the paper that has been published in Physics of Plasmas,30, 2023

Our paper titled “Laboratory study of the PFRC-2’s initial plasma densification stages” is here

The paper titled ” Laboratory study of the PFRC-2’s initial plasma densification stages” published in Physics of Plasmas, Volume 30, October 2023 talks about our research on Initial plasma densification by odd parity rotating magnetic fields (RMFo) applied to the linear magnetized Princeton field-reversed configuration (PFRC-2) device with fill gases at pressures near 1 mTorr proceeds through two phases: a slow one, followed by fast one. Over most of the range of experimental parameters investigated, as the PFRC-2 axial magnetic field strength was increased, RMFo power decreased, gas fill pressure lowered, or lower atomic mass unit (AMU) fill gas used, the duration of the slow phase lengthened from 50 μs to longer than 10 ms after the RMFo power began. The slow phase is explicable to ionization events at low Te, ∼5–7 eV The fast phase requires better power absorption and, more importantly, improved particle and energy confinement.

To find more information, please check the paper.

IAEA Fusion Energy Conference 2023

I attended the International Atomic Energy Agency (IAEA) Fusion Energy Conference (2023) held in London, UK. I was part of the United States of America delegation. My poster was on the business of fusion and particularly about the unique business aspects of PFRC. My poster session was on Saturday.

The first thing I did was visit the exhibitors. ITER had a fascinating booth with an excellent book on the ITER project. They also had a cool flip book showing machine construction. I visited ITER in 2022 so it was fun touching base with them again. 

General Atomics had a booth that highlighted their new Tokamak work. General Atomics has been running DIII-D for years. It is the oldest operating Tokamak in the U.S. Their next Tokamak will build on their extensive experience. I learned more about Tokamak scrape-off layers and neutral beam disruption control from General Atomics scientists.

The EUROfusion booth’s poster had a nice synopsis of the state-of-the-art in magnetic confinement fusion. You can see the Technology Readiness Levels (TRL) levels in the following image.

I talked to a scientist from the United Kingdom about neutron shielding. Even though our machine would not have 14 MeV neutrons it would have some 2.45 MeV neutrons from D-D side reactions. He had ideas for low-mass shielding.

Dr. Ahmed Diallo, Dr. Richard Hawryluk, and Dr. Scott Hsu were representing DOE at the conference. They had many side meetings.

At the banquet, I chatted with engineers working on the UKAEA STEP program. We discussed how to keep the public and politicians interested and involved. The banquet was quite nice.

I talked to many people about our power electronics work funded by ARPA-E GAMOW. Applications include power supplies, neutral beams, radio-frequency heating, and controls. We hope that some of the people I met will become customers.

Our poster was next to the Fusion Industry Association Poster (FIA).  I had many visitors. I was near the University of Wisconsin mirror poster and enjoyed talking about their mirror project. I discussed PFRC transport with a scientist from the UK.

The FIA poster had a picture showing the evolution of the private fusion industry. Notice that we are the first! We didn’t start working on fusion until 1998.

Our poster corner! To the right is a poster from PPPL on lithium walls.

The next IAEA fusion meeting will be in Xi’an China in 2025.

London was fun! I went to The Albert, a pub that survived the blitz. It was built in 1862. The fish and chips were excellent.

I visited Buckingham Palace which was a short walk from my hotel.

London had helpful pedestrian signs.

The Elizabeth Line, London’s latest subway, was gorgeous! It is very comfortable and fast.

A former Royal Armory now houses arts organizations.

The Carlos Acosta Dance Center is at the Armory site.

I discovered the Noble Palace restaurant about a block from my hotel. I visited it twice. Some of the best Chinese food I had ever had. The service was impeccable. The decor was fun.

The Nobel Prize in Physics 2023 and its potential connections to fusion plasmas

Congratulations to the winners of the Nobel Prize in Physics 2023 who created experimental methods for generating attosecond pulses of light! An accessible introduction to the physics behind this prize can be found here.

For a sense of scale, my doctoral thesis work used laser pulses that were nanoseconds, picoseconds, and femtoseconds long, corresponding to one billionth, one trillionth, and one quadrillionth of a second respectively. I used these lasers to create small plasmas (millimeter-sized) in gases, which I would then send a microwave beam to observe, for diagnosing both the gas and plasma (e.g., remote measurements of vector magnetic fields). Attosecond (one quintillionth of a second!) pulses get down to the fastest timescales in atoms, with the potential to track movements and transitions of the electron clouds.

The plasmas I work with nowadays are larger, closer to 10’s of centimeters, in the Princeton Field-Reversed Configuration-2 (PFRC-2) experiment. A femtosecond laser has been applied to the PFRC-2 for measurement of the neutral (non-ionized) atomic hydrogen by Dr. Arthur Dogariu, one of my Ph.D. advisors, see the paper here. Many of the plasma dynamics are closer to micro- and millisecond time-scales, at least a trillion times longer than an attosecond! As plasmas achieve higher temperatures, they gain a large number of fast particles, so we could anticipate some applications of attosecond diagnostics in very high temperature plasmas.

Although it might be a while before we would see attosecond lasers applied in plasma fusion experiments, it is important to think about the possibilities. One paper discusses using high intensity light from packing energy into such a short time for proton-boron fusion generation from a solid. More generally, there are many processes that occur in a plasma which are based in quantum mechanics (ionization, photo-emission, recombination) and a deeper understanding of these processes using attosecond diagnostics can certainly spill over into plasma physics by improving the models of these processes.

PSS SunStation Solar Power System

We are working to develop the Princeton Field Reversed Configuration (PFRC) nuclear fusion power plant. We’ll be at the IAEA Fusion Energy Conference in London this month to present the latest news about PFRC.

We also build SunStation solar power systems. This probably makes us the only fusion company to have delivered fusion power (albeit from the sun) to the grid.

The following figure shows 24 hours of operation on a sunny day. The web interface is provided by the Outback OPTICS RE software.

The area from 14:30 to 17:30 is when cars are being charged. Power consumption is around 300 W including dishwasher, induction cooktop, refrigerator, lights, Internet, and a large screen TV. All of the lights are LED. The house has a geothermal heat pump. The heat pump also preheats water for a gas hot water heater. The house has an energy recovery ventilator that exchanges air every 3 hours. Over three times as much power was sent to the grid as was taken from the grid!

The black bars are the load. Note the jump when a 2021 Ford Mach-E is connected. The Mach-E uses an Aerovironment L2 charger. A 2018 Toyota Prius Prime is also charging. The Prime uses a wall plug and a charging cable. PSE&G has a new program for discounted electric power after 9 p.m. for electric car charging.

Here is a partly sunny day.

The following image shows the power flow. The Lithium Iron Phosphate batteries are at 95%.

4.1 kW is being delivered to the grid. A snapshot of the solar array and\ power flow is below.

You can get a lot of power later in the day. Here it is at 4:23. The high load is due to EV charging.


The solar array is composed of Sharp and Panasonic panels. The Sharp were the original panels and the Panasonic were added when the system was upgraded to a SunStation. SunStation can operate even when the grid is down. It has a transfer switch that automatically cuts the link to the grid when the grid goes down. The battery capacity of 14 kWh is sufficient for about 5 days of operation when the solar input is zero. With normal sunlight, the home can operate indefinitely off-grid. There is no need for a fossil-fuel-based generator.

If you have an existing solar power system you would need to purchase a new inverter to charge batteries. An alternative is a Tesla Powerwall that connects to your AC wires and charges batteries by first rectifying the AC power. Some solar systems use micro-inverters that convert the solar panel’s DC power to AC power at each panel. These would also require something like the Powerwall.

The installation is shown below. The Outback Inverter is on the left. The Outback charges the batteries directly from DC power. The inverter is connected to the Mate3 interface which is connected to a NETGEAR range extender. The batteries are on the right in the cabinet. The battery management system is in the middle. The large boxes on the top prevent arc faults and are required by code. The box on the upper right is the power supply for those boxes. That functionality is now built into the inverters.

Here is a view of the roof. Notice the slight difference in color of the panels.

Contact us for more information and to get a quote!

You can find more information on geothermal from he linked blog post.

Beyond Earth Symposium

The Beyond Earth Institute is conducting the

Beyond Earth Symposium

LEO to Lunar to Living Beyond Earth:
Policy Pathways to Space Migration

November 1-2, 2023

There will be attendees from the U.S. Space Force, The Japan Aerospace Exploration Agency (JAXA), NASA, and many private companies. The Beyond Earth Institute is a non-profit think tank that conducts research and provides analysis for decision-makers. I’ll be attending!

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.