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#1 2016-04-13 09:35:03

Tom Kalbfus
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Registered: 2006-08-16
Posts: 4,401

NASA funds Direct Drive Fusion Propulsion

NASA funds Direct Drive Fusion Propulsion
The Direct Fusion Drive (DFD) concept provides game-changing propulsion and power capabilities that would revolutionize interplanetary travel. DFD is based on the Princeton Field-Reversed Configuration (PFRC) fusion reactor under development at the Princeton Plasma Physics Laboratory. The mission context we are proposing is delivery of a Pluto orbiter with a lander. The key objective of the proposal is to determine the feasibility of the proposed Pluto spacecraft using improved engine models. DFD provides high thrust to allow for reasonable transit times to Pluto while delivering substantial mass to orbit: 1000 kg delivered in 4 to 6 years. Since DFD provides power as well as propulsion in one integrated device, it will also provide as much as 2 MW of power to the payloads upon arrival. This enables high-bandwidth communication, powering of the lander from orbit, and radically expanded options for instrument design. The data acquired by New Horizons' recent Pluto flyby is just a tiny fraction of the scientific data that could be generated from an orbiter and lander. We have evaluated the Pluto mission concept using the Lambert algorithm for maneuvers with rough estimates of the engine thrust and power. The acceleration times are sufficiently short for the Lambert approximation, i.e. impulsive burns, to have some validity. We have used fusion scaling laws to estimate the total mission mass and show that it would fit within the envelope of a Delta IV Heavy launch vehicle. Estimates of the amount of Helium 3 required to fuel the reactor are within available terrestrial stores.
pfrc.jpg
PFRCexperiments.jpg
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In this Phase I study, we propose to analyze the Pluto mission concept using new models of the engine. We will develop an optimal trajectory including limits on the thrust steering and range of throttle. The throttling of the thrust and specific impulse will affect the efficiency, which we have not yet attempted to model.

Direct Fusion Drive is a unique fusion engine concept with a physically feasible approach that would dramatically increase the capability of outer planet missions. The fusion-enabled Pluto mission proposed here is credible, exciting, and the benefits to this and all outer planet missions are difficult to overstate. The truly game-changing levels of thrust and power in a modestly sized package could integrate with our current launch infrastructure while radically expanding the science capability of these missions

There was a 2014 presentation on the Princeton Direct drive fusion concepts. and a work from 2013

• The DFD design envelope fits between traditional chemical, electric and nuclear propulsion methods.
• Fusion products of the deuterium-helium-3 (D/He3) reaction have a very high exhaust velocity: 25,000 km/s
• We can convert some of their kinetic energy into thrust by transferring energy from the fusion products.
directfusionprinceton.png
The work has been covered at Nextbigfuture back in 2014 and in 2013

This is different than the John Slough's direct fusion drive rocket design. John Slough also had NASA funding.

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#2 2021-09-14 12:11:53

tahanson43206
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Registered: 2018-04-27
Posts: 16,749

Re: NASA funds Direct Drive Fusion Propulsion

RobertDyck appears to have found an update to this original topic by Tom Kalbus ...

http://newmars.com/forums/viewtopic.php … 00#p185000

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#3 2021-09-14 12:54:38

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 7,781
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Re: NASA funds Direct Drive Fusion Propulsion

Ok, merging topics...

phys.org: Spacecraft design could get to Titan in only 2 years using a direct fusion drive
impatientasp.jpg

The concept fusion drive, called a direct fusion drive (or DFD), is in development at the Princeton Plasma Physics Laboratory (PPPL). Scientists and Engineers there, led by Dr. Samuel Cohen, are currently working on the second iteration of it, known as the Princeton field reversed configuration-2 (PFRC-2). Eventually, the system's developers hope to launch it into space to test, and eventually become the primary drive system of spacecraft traveling throughout the solar system.

Wikipedia: Direct Fusion Drive

Principle
In the DFD system, the plasma is confined in a torus-like magnetic field inside of a linear solenoidal coil and is heated by a rotating magnetic field to fusion temperatures. Bremsstrahlung and synchrotron radiation emitted from the plasma are captured and converted to electricity for communications, spacecraft station-keeping, and maintaining the plasma's temperature. This design uses a specially shaped radio frequency (RF) "antenna" to heat the plasma. The design also includes a rechargeable battery or a deuterium-oxygen auxiliary power unit to startup or restart DFD.

The captured radiated energy heats to 1,500 K (1,230 °C; 2,240 °F) a He-Xe fluid that flows outside the plasma in a boron-containing structure. That energy is put through a closed-loop Brayton cycle generator to transform it into electricity for use in energizing the coils, powering the RF heater, charging the battery, communications, and station-keeping functions.

Thrust generation
Adding propellant to the edge plasma flow results in a variable thrust and specific impulse when channeled and accelerated through a magnetic nozzle; this flow of momentum past the nozzle is predominantly carried by the ions as they expand through the magnetic nozzle and beyond, and thus, function as an ion thruster.

Projected performance
Analyses predict that the Direct Fusion Drive would produce between 5-10 Newtons thrust per each MW of generated fusion power, with a specific impulse (Isp) of about 10,000 seconds and 200 kW available as electrical power. Approximately 35% of the fusion power goes to thrust, 30% to electric power, 25% lost to heat, and 10% is recirculated for the RF heating.

Note: 10 Newtons thrust = 1.0197162129779 kg-force. Can this be scaled up for TMI for a Large Scale Colonization Ship?

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#4 2021-10-03 12:45:52

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 16,749

Re: NASA funds Direct Drive Fusion Propulsion

For RobertDyck .... there will be a talk on fusion in the upcoming Mars Conference ...

Helicity Space Co-Founder to Address Mars Society Convention about Fusion Drive Concept

The Mars Society is pleased to announce that Dr. Setthivoine You, Co-Founder and Chief Scientist of Helicity Space, will discuss his company’s Helicity Drive, a novel fusion drive concept, during the 24th Annual International Mars Society Convention, set for October 14-17, 2021.

Helicity Space is developing an in-space fusion propulsion and power technology, critical to enabling humanity’s access to the solar system, with a Helicity Drive-powered flight to Mars expected to take two months, without planetary alignment.

Dr. You received his M.S. degree and Ph.D. in physics from the Imperial College London, and spent 18 years involved in experimental and theoretical research in plasma physics at the University of Washington, CalTech, and the University of Tokyo before entering the private sector.

This year’s virtual Mars Society convention will be free of charge (although donations are welcomed). For complete details, including online registration, a list of confirmed speakers, and sponsorship opportunities, please click here. Regular updates will be posted in the coming weeks on the Mars Society web site and its social media platforms.


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