Radioisotope Portable Power Unit: A Compact, Long-Duration Radioisotope Power Unit for Autonomous Systems

Long-duration autonomous systems require continuous power where solar illumination is unavailable, battery-only storage is insufficient, and maintenance access is impossible. RPPU-0 is a compact, sealed, decay-driven radioisotope power architecture that directs charged-particle flux from radioisotope decay through a governed extraction topology and regulated DC bus.
The paper defines a governed decay-ionised domain within a static physical enclosure. Dynamic governed topology constraints inherited from IDG-2 define the permitted field-state envelope across the full decay life. Field-assisted extraction, watts-per-curie bus regulation, daughter-product filtering, feedthrough degradation management, inductive energy recovery, safety interlocks, environmental hardening, telemetry, and flight housing are integrated as one sealed RPPU-0 module.
Version 5 extends the long-duration engineering package with two passive, sealed-interface elements. The Metamaterial Boundary Layer (MBL) smooths selected interface gradients, reduces mapped local harmonic content, and reinforces the designed curvature topology. GECDS-IDG is a segmented, electrically isolated governed eddy-current damping shell that manages selected low-frequency transient response around the curvature hardware and structural frame. Curvature remains the primary stability mechanism. DIGSP-IDG coordinates the permitted topology, boundary condition, damping response, extraction state, safety state, and regulated bus through its established supervisory hierarchy.
RPPU-0 is designed as a 24 VDC nominal power architecture in the 5–50 W class. Its platform expressions include lunar and planetary robotics, deep-space micro-probes, surface infrastructure, harsh-environment industrial sensors, emergency autonomous power nodes, and RPPU-Lite battery-sustainment configurations for long-duration UAV and autonomous-system operations. In the RPPU-Lite expression, the sealed core maintains the battery reserve through continuous governed DC delivery while the battery provides propulsion, payload, manoeuvre, and avionics peaks.
The manuscript develops the RPPU-0 system architecture, power-bus specification, environmental hardening, packaging, long-duration control, safety envelope, platform expressions, comparative architecture, and RPPU-1 handoff. Its evidence pathway is defined through the G1–G10 graduation programme, which carries the sealed core through bench integration, vacuum qualification, environmental qualification, and flight-hardware transfer. Version 5 includes a hardware safety layer independent of DIGSP software, a dose-rate term in the feedthrough insulation model, radiation-tolerant Sm2Co17 mirror magnets, and an accelerated-dose qualification gate G10.
RPPU-0 is an author-owned engineering integration architecture. The paper defines the sealed decay-ionised core, extraction, boundary, damping, safety, and bus package required for long-duration autonomous power deployment.

NA

1. Related Works [Google Scholar] [Crossref]

2. Griffiths, W. MPE-1: Stability as a Governed Outcome. Wayne Griffiths, 2025. [Google Scholar] [Crossref]

3. Griffiths, W. MPE-5: Topology State Vector and Governability Map. Wayne Griffiths, 2025. [Google Scholar] [Crossref]

4. Griffiths, W. MPE-6: Lambda-Governance in Isolated Plasmas. Wayne Griffiths, 2025. [Google Scholar] [Crossref]

5. Griffiths, W. MPE-8: Dynamic Curvature Capacity and Suppression-Field Invariant. Wayne Griffiths, 2025. [Google Scholar] [Crossref]

6. Griffiths, W. IDG-1: Physics Basis for a Unified Radioisotope-Driven Governed Topology. Wayne Griffiths, 2026. [Google Scholar] [Crossref]

7. Griffiths, W. IDG-2: Dynamic Governance and Invariant Test. Wayne Griffiths, 2026. [Google Scholar] [Crossref]

8. Griffiths, W. IDG-3: Field-Assisted Extraction and Watts-Per-Curie Scaling. Wayne Griffiths, 2026. [Google Scholar] [Crossref]

9. Radioisotope and Decay Physics [Google Scholar] [Crossref]

10. Krane, K. Introductory Nuclear Physics. Wiley, 1987. [Google Scholar] [Crossref]

11. Knoll, G. Radiation Detection and Measurement. Wiley, 2010. [Google Scholar] [Crossref]

12. NIST ESTAR Database. Stopping Powers and Ranges for Electrons. NIST. [Google Scholar] [Crossref]

13. Plasma Confinement [Google Scholar] [Crossref]

14. Chen, F. F. Introduction to Plasma Physics and Controlled Fusion. Springer, 2016. [Google Scholar] [Crossref]

15. Lieberman, M., Lichtenberg, A. Principles of Plasma Discharges and Materials Processing, 2nd ed. Wiley, 2005. [Google Scholar] [Crossref]

16. Post, R. F., Rosenbluth, M. N. Electrostatic Instabilities in Finite Mirror-Confined Plasmas. Phys. Fluids 9, 730, 1966. [Google Scholar] [Crossref]

17. Space-Charge and Extraction [Google Scholar] [Crossref]

18. Child, C. D. Discharge from Hot CaO. Phys. Rev. (Series I) 32, 492, 1911. [Google Scholar] [Crossref]

19. Langmuir, I. The Effect of Space Charge and Residual Gases on Thermionic Currents in High Vacuum. Phys. Rev. 2, 450, 1913. [Google Scholar] [Crossref]

20. Radioisotope Power (Comparative) [Google Scholar] [Crossref]

21. NASA. RTG Systems Engineering Overview. NASA Technical Reports. [Google Scholar] [Crossref]

22. Lee, Y., Bairstow, B. Radioisotope Power Systems Reference Book for Mission Designers and Planners. JPL Publication 15-6, NASA Jet Propulsion Laboratory, 2015. [Google Scholar] [Crossref]

23. Zeno Power. Harmonia: NASA Tipping Point radioisotope power system for 14-day lunar night and permanently shadowed regions. July 2023. [Google Scholar] [Crossref]

24. Deep Space Energy. Radioisotope-based lunar power generator, pre-seed funding announcement. Feb 2026. [Google Scholar] [Crossref]

• Design and Implementation of an Intelligent Sensor-Integrated Dehydration System for Sustainable Post-Harvest Preservation