Ultra-Dense Deuterium Fueled Starship
We have finally arrived at the last vehicle presented by Project Icarus’ designers at the British Interplanetary Society on October 21 and 22nd, 2013. In the landscape of vehicle design studies this one is the most ambitious yet, as it uses a theoretical fuel source known as D(-1) * Ultra-Dense Deuterium – hydrogen in a special Rydberg State which would allow D-D fusion to take place relatively easily
If you are enjoying our work as much as we are, consider supporting our research fundraiser. We are extending this campaign until all vehicles have been refined and presented, with deadline around November 15th. All donations made to Icarus Interstellar throughout the campaign will be channeled to support the “2013 Project Icarus Design Competition”, in support of student and designer travel expense support (no wages are paid – some of you have been asking).
In appreciation of your support, donors will receive:
- $10 Your name listed in the acknowledgements of the final publication.
- $20 Icarus Interstellar Lapel Badge (and above)
- $50 Icarus Mug and t-Shirt (and above)
- $100 Advance copies of the INTERNAL Spacecraft Design studies (and above)
- $101 SPECIAL donations over $100 will receive an exclusive media pack containing HIGH RESOLUTION SPACECRAFT ENGINEERING DESIGNS rendered expertly by Adrian Mann (www.bisbos.com) (including all of the above!)
This will be the last announcement of a vehicle study. The next announcement will contain the winner of the Project Icarus Design Competition/ At that time, the reports and media package will be electronically shared with everyone who supported our designers at the appropriate amount!
UDD Icarus Concept Overview
The idea about using UDD as primary fuel to propel an interstellar probe stems from the extraordinary properties that UDD is claimed to have. The immense density of UDD in its natural state alleviates the otherwise necessary compression stage of a target fuel pellet (such as in classic Inertial Confinement Fusion systems (ICF)), which in turn provides a number of possible improvements for the overall design of the propulsion system. However, the topic of actual UDD existence is still somewhat controversial as no third-party experimental results exists and most of the published work stems from a single group of scientists at the University of Gothenburg (Sweden). Nonetheless, the UDD concept was primarily envisioned as a hypothetical platform which would explore the option of potential use of UDD as primary fuel and the subsequent consequences regarding the design.
UDD is an exotic form of metallic hydrogen (Rydberg matter) and is supposedly found along with the regular metallic hydrogen in the experiments performed by Dr. Holmlid and his group at the University of Gothenburg. The list of its exotic properties is long and it includes superconductivity and superfluidity at room temperature as well as its primary characteristic: enormous density. The estimates of its density vary from 1028 to 1029 cm-3 based on theoretical predictions and experimental observations. This density level is roughly 150 times higher than the originally predicted National Ignition Facility ICF target at peak compression. The enormous density would imply that, as shown by Winterberg [1], a very low energy input is required for the ignition of the fusion target, while completely circumventing the need for target compression and thus a series of physics issues that come along with it. The numbers estimate that a single PW-scale, 3 kJ laser beam would be sufficient to start the fusion reaction. This further means that the overall fusion-driver system for the ignition would comprise of only one laser, instead of many (i.e. 100 or 200) lasers required for the conventional ICF schemes.
The UDD Icarus concept is to be a 2-stage acceleration vehicle, achieving a cruising velocity of 0.05c, while deceleration phase is also a 2-stage magsail-fusion hybrid system which would allow for a rendezvous mission. Both stages are dual-engine, which significantly increases the robustness of the design. Total rendezvous mission time to a-Centauri sums up to be appropriately 100 years.
The second stage plays the role of final deceleration stage, using the same engine and architecture as during the acceleration phase. The main technical solution that requires pointing out is that after 2nd stage acceleration has been completed, most (apprix 68%) of the radiator mass is dropped. At 0.368 ly before a-Centauri the magsail is deployed. The magsail design is completely based on the Matlab code from Raible’s semester work [2] and has been calculated to have a mass of 238 t. After the magsail deceleration phase the magsail system is also dropped, bringing the payload mass down to 612 t. When the reverse burn is completed, the final payload mass is 320 t, of which 150 t is scientific payload. Figure 1 shows a simplified breakdown of the mission architecture.
Figure 1: Simplified mission architecture.
Due to inherent limit of DD fuel (low energy output in comparison to i.e. D3He), the specific impulse of the vehicle remains fairly low at approximately 550,000 s, which results in large fuel mass of 75,000 t. This imposes further, stricter mass requirements for the deceleration systems (magsail) and other sub-systems, in particular the secondary power system, shielding and waste heat disposal as primary mass contributors.
It is important to point out that the fuel stored in the tanks would be regular deuterium and that the conversion of deuterium to UDD would be carried out on board. This is due to predicted superfluous properties of UDD, as well as due to potential instability of the fuel (due to extreme densities and low ignition energy requirements, there is a statistical chance that large amounts of UDD would undergo a spontaneous fusion reaction).
UDD engines have four very important advantages in comparison to any other fusion concept currently (theoretically) available. These are:
- Complete circumvention of the target compression stage, allowing for direct ignition [3] (absence of hydrodynamic instabilities and reduced plasma-laser interaction consequences).
- Single PW-scale laser target ignition which massively reduces the system complexity and thus mass.
- Virtually unlimited gains, depending solely on the size of the target. This of course greatly increases the deliverable performance of the whole concept.
- Uses D in its tanks and converts it to UDD on-board to be delivered to the reaction chamber (nozzle). D is abundant on Earth, stable, non-toxic and orders of magnitude cheaper to produce than i.e. 3He.
- Combined, the above allow for multi-engine, modular design which greatly increases overall system robustness and reliability, while significantly reducing the development and building costs.
On the other hand, there is a single, but crucial, issue that severely influences the overall viability of UDD-based engines.
- Viable proof of claimed UDD characteristics and mass UDD production.
Namely, the vast majority of the UDD-related papers has been published by a single scientific group at University of Gothenburg, Sweden, led by Dr. L. Holmlid [4-7]and a few papers from Dr. F. Winterberg [1, 8]who tried presenting a theoretical background to the UDD concept. To author’s knowledge, currently there are no third-party confirmations about UDD observations and generally very few discussions about it in the scientific community.
In conclusion: if UDD, its properties and mass-production are confirmed to be real, UDD would cause a major revolution in the world of nuclear fusion. However, due to relative scientific obscurity, lack of third-party result replications and theoretical vagueness of the UDD production process, that one “if” is a big one.
References:
1. Winterberg, F., Ultra-dense deuterium and cold fusion claims. Physics Letters A, 2010. 374(27): p. 2766-2771.
2. Raible, M., Concept Development for a Magnetic Sail Deceleration System. Technical University Munich.
3. Stanic, M., Project Icarus: Analysis and Comparison of Inertial Confinement Fusion Lasers and Predictions for Future Use in Space Propulsion, in 63rd International Astronautical Congress. 2012: Naples, Italy.
4. Andersson, P.U. and L. Holmlid, Ultra-dense deuterium: A possible nuclear fuel for inertial confinement fusion (ICF). Physics Letters A, 2009. 373(34): p. 3067-3070.
5. Badiei, S., P.U. Andersson, and L. Holmlid, Production of ultradense deuterium: A compact future fusion fuel. Applied Physics Letters, 2010. 96(12): p. 124103-3.
6. Andersson, P.U. and L. Holmlid, Superfluid ultra-dense deuterium at room temperature. Physics Letters A, 2011. 375(10): p. 1344-1347.
7. Andersson, P.U., B. Lonn, and L. Holmlid, Efficient source for the production of ultradense deuterium D(-1) for laser-induced fusion (ICF). Review of Scientific Instruments, 2011. 82(1): p. 013503-8.
8. Winterberg, F., The Release of Thermonuclear Energy by Inertial Confinement: Ways Toward Ignition. 2010, New Jersey, London, Singapore, Beijing, Hong Kong, Taipei, Chennai: World Scientific.
Next week we will be announcing the winner and closing out this exciting chapter in Icarus Interstellar’s research portfolio. We could not have done it without your interest, support and amazing feedback on the details shared so far on these vehicles!
Thank you!
/Icarus
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