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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 109 records · Page 6

Effects of Proton Irradiation on GaN Vacuum Electron Nanodiodes

Gallium nitride (GaN)-based nanoscale vacuum electron devices, which offer advantages of both traditional vacuum tube operation and modern solid-state technology, are attractive for radiation-hard applications due to the inherent radiation hardness of vacuum electron devices and the high radiation tolerance of GaN. Here, we investigate the radiation hardness of top-down fabricated n-GaN nanoscale vacuum electron diodes (NVEDs) irradiated with 2.5-MeV protons (p) at various doses. We observe a slight decrease in forward current and a slight increase in reverse leakage current as a function of cumulative protons fluence due to a dopant compensation effect. The NVEDs overall show excellent radiation hardness with no major change in electrical characteristics up to a cumulative fluence of 5E14 p/cm 2 , which is significantly higher than the existing state-of-the-art radiation-hardened devices to our knowledge. In conclusion, the results show promise for a new class of GaN-based nanoscale vacuum electron devices for use in harsh radiation environments and space applications.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Resilience of High-Efficiency CdSeTe:As and CdSeTe:Cu Solar Cells to Proton Irradiation

Power generation in space is currently dominated by expensive III-V multi-junction photovoltaic (PV) devices and cheap crystalline silicon (c-Si) PV devices. Both of these technologies degrade rapidly in proton-radiation-rich space environments, such as the Van Allen belt. The present study of cadmium selenide telluride- (CdSeTe-) based PV devices exposed to 150-to-1500 keV proton irradiation with fluences up to 9 x 1013 cm-2 reveal a more radiation-hard alternative to III-V and c-Si PV technologies. We report on measurement and analysis of current density vs voltage (JV), external quantum efficiency (EQE), external radiative efficiency, and capacitance vs voltage (CV) characteristics. JV characteristics of As-doped CdSeTe devices show 80% remaining power conversion efficiency (PCE) relative to unexposed controls when exposed to 650 keV protons at a fluence of 1012 cm-2. Under these same irradiation conditions, Cu-doped CdSeTe devices demonstrate an even better 95% PCE retention compared with unirradiated control devices. Evidence of radiation-induced absorber p-type doping compensation is observed in the glass-side EQE at 0 V and CV characteristics of most of the irradiated CdSeTe:As devices, but clear compensation is evident only for the most heavily irradiated CdSeTe:Cu devices. Elevated blue-green photocurrent in the film-side 0 V EQE suggests a buried junction in the most heavily irradiated CdSeTe:As devices. Although CdSeTe:Cu devices are the more resilient of the CdSeTe structures, both CdSeTe-based technologies are radiation-hard when compared to c-Si and III-V multi-junction PV.

14 SOLAR ENERGY↗

Low-Earth Orbit Flight Test of an Inflatable Decelerator (LOFTID) Mission Overview and Science Return

The Low-Earth Orbit (LEO) Flight Test of an Inflatable Decelerator (LOFTID) mission was the culmination of two decades of research and development led by NASA Langley Research Center for Hypersonic Inflatable Aerodynamic Decelerator (HIAD) technology. A HIAD aeroshell can be hard packed into a small volume for launch and then deployed prior to atmospheric entry for stable aerodynamic deceleration through the atmosphere. Much larger than traditional fixed diameter aeroshells that are constrained by the size of launch vehicle shrouds, inflatable decelerators create more drag and start the deceleration process in the upper reaches of the atmosphere with greater efficiency and stability. Large deployable heatshields enable spacecraft to carry bigger, heavier payloads, including scientific instruments and human support systems for planetary landing and exploration. The success of the LOFTID mission could enable new NASA missions to Mars (including access to higher altitudes than currently possible), Venus, and most solar system destinations with atmospheres, as well as cost-effective payload returns to Earth. With its unique 6m diameter inflatable heatshield, LOFTID was the first-of-a-kind orbital reentry flight, and the largest blunt body atmospheric entry of any kind. On November 10, 2022, the LOFTID aeroshell endured the harsh environments of atmospheric reentry while exhibiting stable aerodynamics through the entire spectrum of hypersonic, supersonic, transonic, and subsonic flight. The demonstration confirmed the HIAD technology structural and thermal performance as the aeroshell protected the 1100 kg Reentry Vehicle (RV) entering Earth’s atmosphere at 8 km/s, reaching Mach 30, and experiencing 9.5 g deceleration before deploying parachutes and gently splashing down in the Pacific Ocean, where it was recovered in excellent condition. The LOFTID aeroshell was exposed to an aeroheating environment representative of many Mars and LEO HIAD applications, and successfully demonstrated the ability of the heat-affected inflatable structure to withstand aerodynamic forces that exceeded those expected at Mars. This mission further demonstrated the viability of HIAD technology to deliver large payloads safely and accurately through an atmosphere via a controlled entry, descent, and landing. Whereas LOFTID was indeed a first-of-a-kind flight for an inflatable heatshield, its remarkable performance assured that it will not be the last of its kind.

J M Dinonno↗

Low-Earth Orbit Flight Test of an Inflatable Decelerator (LOFTID) Mission Overview and Science Return

The Low-Earth Orbit (LEO) Flight Test of an Inflatable Decelerator (LOFTID) mission was the culmination of two decades of research and development led by NASA Langley Research Center for Hypersonic Inflatable Aerodynamic Decelerator (HIAD) technology. A HIAD aeroshell can be hard packed into a small volume for launch and then deployed prior to atmospheric entry for stable aerodynamic deceleration through the atmosphere. Much larger than traditional fixed diameter aeroshells that are constrained by the size of launch vehicle shrouds, inflatable decelerators create more drag and start the deceleration process in the upper reaches of the atmosphere with greater efficiency and stability. Large deployable heatshields enable spacecraft to carry bigger, heavier payloads, including scientific instruments and human support systems for planetary landing and exploration. The success of the LOFTID mission could enable new NASA missions to Mars (including access to higher altitudes than currently possible), Venus, and most solar system destinations with atmospheres, as well as cost-effective payload returns to Earth. With its unique 6m diameter inflatable heatshield, LOFTID was the first-of-a-kind orbital reentry flight, and the largest blunt body atmospheric entry of any kind. On November 10, 2022, the LOFTID aeroshell endured the harsh environments of atmospheric reentry while exhibiting stable aerodynamics through the entire spectrum of hypersonic, supersonic, transonic, and subsonic flight. The demonstration confirmed the HIAD technology structural and thermal performance as the aeroshell protected the 1100 kg Reentry Vehicle (RV) entering Earth’s atmosphere at 8 km/s, reaching Mach 30, and experiencing 9.5 g deceleration before deploying parachutes and gently splashing down in the Pacific Ocean, where it was recovered in excellent condition. The LOFTID aeroshell was exposed to an aeroheating environment representative of many Mars and LEO HIAD applications, and successfully demonstrated the ability of the heat-affected inflatable structure to withstand aerodynamic forces that exceeded those expected at Mars. This mission further demonstrated the viability of HIAD technology to deliver large payloads safely and accurately through an atmosphere via a controlled entry, descent, and landing. Whereas LOFTID was indeed a first-of-a-kind flight for an inflatable heatshield, its remarkable performance assured that it will not be the last of its kind.

John M DiNonno↗

Radiation hardness characterization of LKH-5 scintillating glass

Radiation hardness is an important property to examine in scintillators to help determine their expected lifetime in application cases where significant radiation dose is expected. Industrial imaging systems using 9 MV linear accelerators for x-ray radiography are one such application where significant radiation doses are expected to the scintillators used. Cadmium tungstate scintillators (CWO) and Thallium doped Cesium Iodide scintillators (CsI(Tl)) are used in some high energy cargo x-ray radiography systems. However, CWO has a high manufacturing cost for adequately uniform crystals and CsI(Tl) does not have sufficient radiation hardness. LKH-5 glass is being investigated as a potential low cost replacement for CWO and CsI(Tl). In this experiment 36 samples of a terbium doped silicate glass called LKH-5 were irradiated at doses up to 5 MRad using a 9 MV linear accelerator, and the change in their transmission properties was observed. Additionally, the glass was discovered to be a radiation hard glass due to the relatively small change in the transmission of the glass: less than 3% per cm at its emission peak of 550 nm and 5 MRad. This is similar to CWO which has a reported reduction in transmitted light of 2% per cm at 5 MRad and the emission peak of 475 nm and better than CsI(Tl) which is reported to have a reduction in transmitted light of 5% per cm at the emission peak of 550 nm and 4.2 MRad dose. Furthermore, an annealing procedure is described that returned the transmission of the glass to pre-irradiation values.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

Experimental study of hot electron generation in shock ignition relevant high-intensity regime with large scale hot plasmas

In the shock ignition (SI) laser fusion scheme, hot electrons generated by the laser spike pulse can either preheat the fuel or strengthen the ignition shock, depending on the hot electron characteristics. We conducted a planar target experiment on the OMEGA-EP laser facility and characterized the temperature and total energy of hot electrons generated from a kilojoule-class 100-ps infrared (IR) or a 1-ns ultraviolet (UV) laser interacting with a large (L n ~330-450 μm) and hot (T e ~1-2 keV) coronal plasma at the SI-relevant intensities (~10 16 W/cm 2 ). The IR laser converts ~2.5% energy into hot electrons with T hot ~ 60–90 keV, while the UV laser couples 0.8% ± 0.7% energy into T hot =27 ± 9 keV hot electrons. The IR-produced hot electrons yield five times higher Cu Kα emission than the UV case, confirming the higher electron conversion efficiency with the IR laser. The low energy conversion from the UV laser to hot electrons may be due to the refraction of the off-normal incident laser in the large coronal plasma. These findings are the first comparisons of hot electron generation between the IR and UV pulses at kilojoule scales in SI-relevant large-scale plasmas. The findings may expand the SI design space to include IR lasers as the possible spike lasers.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

Direct comparison of wire, foil, and hybrid X-pinches on a 200 kA, 150 ns current driver

Wire X-pinches (WXPs) have been studied comprehensively as fast (~1 ns pulse width), small (~1 μm) x-ray sources, created by twisting two or more fine wires into an “X” to produce a localized region of extreme magnetic pressure at the cross-point. Recently, two alternatives to the traditional WXP have arisen: the hybrid X-pinch (HXP), composed of two conical electrodes bridged by a thin wire or capillary, and the laser-cut foil X-pinch (LCXP), cut from a thin foil using a laser. We present a comparison of copper wire, hybrid, and laser-cut foil X-pinches on a single experimental platform: UC San Diego’s ~200 kA, 150 ns rise time GenASIS driver. All configurations produced 1–2 ns pulse width, ≤5 μm soft x-ray (Cu L-shell, ~1 keV) sources (resolutions diagnostically limited) with comparable fluxes. WXP results varied with linear mass and wire count, but consistently showed separate pinch and electron-beam-driven sources. LCXPs produced the brightest (~1 MW), smallest (≤5 μm) Cu K-shell sources, and spectroscopic data showed both H-like Cu K α lines indicative of source temperatures ≥2 keV, and cold K α (~8050 eV) characteristic of electron beam generated sources, which were not separately resolved on other diagnostics (within 1–2 ns and ≤200 μm). HXPs produced minimal K-shell emission and reliably single, bright, and small L-shell sources after modifications to shape the early current pulse through them. Benefits and drawbacks for each configuration are discussed to provide potential X-pinch users with the information required to choose the configuration best suited to their needs.

42 ENGINEERING↗

Systems-To-Atoms (S2A): enabling hydrogen for climate security

The project addresses a critical gap in hydrogen infrastructure by integrating system-level energy models with atomic-scale material simulations in a unified Systems-to-Atoms (S2A) framework. The motivation stems from the need to develop efficient, cost-effective, and durable hydrogen transport and utilization technologies to support decarbonization of hard-to-electrify sectors such as heavy-duty transportation. Current system models lack awareness of material performance mechanisms, while material-scale models do not account for system-level usage and variability. To bridge this divide, the team developed a co-simulation capability linking techno-economic analyses, reactor/process-flow modeling, and molecular-scale catalysis simulations. Applied to hydrogen delivery in California, the framework enabled comparative evaluations of compressed, cryogenic, and liquid organic hydrogen carrier (LOHC) pathways, highlighting how catalyst operation and unit process efficiency influence overall performance. The results demonstrate that no single material or transport mode is universally optimal; instead, heterogeneous solutions tuned to specific operational contexts deliver better performance. The project delivers a new capability for cross-scale material co-design, advancing hydrogen infrastructure readiness and informing DOE and LLNL missions in climate and energy resilience.

organic↗

Up, Up and Away: Arc Minute Pointing at 130,000 Feet

The InFOC-S X-ray telescope was launched September 16, 2004 aboard a 40 million cubic foot zero pressure high altitude balloon. Its primary objective was to demonstrate advances in hard X-ray focusing optics technology by flying an incident grazing mirror developed in cooperation between NASA Goddard Space Flight Center and Nagoya University, Japan. Launched from Ft. Sumner, NM and recovered near Wickenburg, AZ, the payload successfully collected photons from several X-ray sources during its 27 hour flight at a float altitude of 130,000 feet. To accommodate the instrument's narrow field of view, a precision arc-minute attitude determination and control systems was flown. This paper describes the application of a traditional spacecraft star tracker gyro based attitude determination and control system to the balloon problem. The control system architecture is presented, hardware identified, and software outlined. Simulated results are compared against actual flight data, with recommendations for enhanced performance identified.

Freesland, Doug↗

Evolution of Requirements and Assumptions for Future Exploration Missions

NASA programs are maturing technologies, systems, and architectures to enabling future exploration missions. To increase fidelity as technologies mature, developers must make assumptions that represent the requirements of a future program. Multiple efforts have begun to define these requirements, including team internal assumptions, planning system integration for early demonstrations, and discussions between international partners planning future collaborations. For many detailed life support system requirements, existing NASA documents set limits of acceptable values, but a future vehicle may be constrained in other ways, and select a limited range of conditions. Other requirements are effectively set by interfaces or operations, and may be different for the same technology depending on whether the hard-ware is a demonstration system on the International Space Station, or a critical component of a future vehicle. This paper highlights key assumptions representing potential life support requirements and explanations of the driving scenarios, constraints, or other issues that drive them.

Anderson, Molly↗

Annual Conference on Nuclear and Space Radiation Effects, 14th, College of William and Mary, Williamsburg, Va., July 12-15, 1977, Proceedings

Topics related to processing and hardness assurance are considered, taking into account the radiation hardening of CMOS technologies, technological advances in the manufacture of radiation-hardened CMOS integrated circuits, CMOS hardness assurance through process controls and optimized design procedures, the application of operational amplifiers to hardened systems, a hard off-the-shelf SG1524 pulse width modulator, and the gamma-induced voltage breakdown anomaly in a Schottky diode. Basic mechanisms are examined, giving attention to chemical and structural aspects of the irradiation behavior of SiO2 films on silicon, experimental observations of the chemistry of the SiO2/Si interface, leakage current phenomena in irradiated SOS devices, the avalanche injection of holes into SiO2, the low-temperature radiation response of Al2O3 gate insulators, and neutron damage mechanisms in silicon at 10 K. Other subjects discussed are related to radiation effects in devices and circuits, space radiation effects, and aspects of simulation, energy deposition, and dosimetry.

Stahl, R. H.↗

Hard X-Ray And Wide Focusing Telescopes

The development of a hard X-ray telescope requires new technology for both substrates and coatings. Our activities in these two areas were carried out virtually in parallel during most of the past few years. They are converging on the production of our first integral conical, substrate electroformed mirror that will be coated with a graded d-spacing multilayer. Its imaging properties and effective area will be measured in hard X-ray beams. We discuss each of these activities separately in the following two sections.

Gorenstein, Paul↗

Next-Generation Hard X-ray Missions: SuperHERO and HEROIX

High-energy X-ray observations have transformed our understanding of astrophysical systems where non-thermal processes dominate, from shock-accelerated particles in supernova remnants to relativistic jets and hot coronae in active galactic nuclei. NuSTAR’s pioneering focusing images of the hard X-ray sky have demonstrated the immense scientific potential of this band, while also highlighting how limited angular resolution constrains our ability to fully characterize complex physical processes in faint extended sources and resolving faint sources in crowded sky regions. In this presentation, I will discuss a pathway to overcome these challenges through NASA Marshall Space Flight Center’s replicated NiCo full-shell X-ray mirror technology. Specifically, I will discuss the SuperHERO hard X-ray telescope to achieve better than 10-arcsecond half-power diameter (HPD) angular resolution on a balloon flight observing the Crab Nebula, and the High EneRgy Observatory for Imaging X-rays (HEROIX) Medium-Class Mission concept to achieve an integrated effective area of 570 cm2 at 30 keV with 5 arcsec HPD angular resolution.

AGN↗

Gate Drive Technology Evaluation and Development to Maximize Switching Speed of SiC Discrete Devices and Power Modules in Hard Switching Applications

To understand the limitation of maximizing the switching speed of SiC low current discrete devices and high current power modules in hard switching applications, double pulse tests are conducted and the testing results are analyzed. For power modules, the switching speed is generally limited by the parasitics rather than the gate drive capability. For the discrete SiC device, the conventional voltage source gate drive (VSG) is not sufficient to maximize the switching speed even if the external gate resistance is minimized. The limitation of existing current source gate drives (CSG) are analyzed, and a CSG dedicated for SiC discrete devices is proposed, which can provide constant current during the switching transient regardless of the high Miller voltage and large internal gate resistance. Compared with the conventional VSG, the proposed CSG achieves 67% faster turnon time and 50% turn-off time, and 68% reduction in switching loss at full load condition.

Handong Gui↗

Low-Earth Orbit Flight Test of an Inflatable Decelerator (LOFTID) Mission Overview, Science Return, and Future Applications of This Technology

The Low-Earth Orbit (LEO) Flight Test of an Inflatable Decelerator (LOFTID) mission was the culmination of two decades of research and development for Hyper-sonic Inflatable Aerodynamic Decelerator (HIAD) technology. LOFTID was a project overseen by the Technology Demonstration Mission (TDM) program within NASA’s Space Technology Mission Directorate. The success of the LOFTID mission could enable new NASA missions to Mars, Venus, and most solar-system destinations with atmospheres, as well as cost-effective payload returns to Earth, including in-space manufactured materials and launch vehicle asset recovery. LOFTID, with its unique inflatable heat shield, was the first-of-a-kind orbital reentry flight, and the largest blunt body atmospheric entry of any kind. On November 10, 2022, just over 10 years since the previous flight test of the smaller sub-orbital Inflatable Reentry Vehicle Experiment-3 (IRVE-3) [1], NASA Langley Research Center, with partner United Launch Alliance (ULA), successfully launched and achieved reentry and recovery of the LOFTID Reentry Vehicle (RV), further demonstrating the viability of the HIAD technology for large-diameter, inflatable heat shields to safely and accurately deliver large payloads through an atmosphere via a controlled descent and landing. Launching as a secondary payload with the Joint Polar Satellite System 2 (JPSS-2) from Vandenberg Space Force Base, California, stowed inside an ex-tended payload adapter of the Atlas V 401 launch vehicle, the LOFTID mission officially began after the JPSS-2 payload was delivered to its orbit by the Centaur second stage. The LOFTID RV was flying solo on its spin-stabilized ballistic reentry trajectory about one hour after launch, and the flight ended approximately one hour later with a gentle splashdown under parachute in the Pacific Ocean off the east coast of Hawaii, where the RV was recovered and later shipped back to NASA Langley. LOFTID endured the harsh environments of atmospheric reentry while demonstrating stable aerodynamics through the entire spectrum of hypersonic, supersonic, transonic, and subsonic flight. The LOFTID RV was exposed to an aeroheating environment representative of many Mars and LEO HIAD applications, while successfully demonstrating the ability of the heat-affected inflatable structure to with-stand aerodynamic forces that exceeded those expected at Mars. This flight demonstration of a 6m diameter HIAD confirmed the technology structural and thermal performance as it protected the 1100kg RV entering Earth’s atmosphere at 8 km/s, reaching Mach 30, and experiencing 9g deceleration before deploying parachutes and splashing down in the Pacific Ocean. HIAD technology involves an aeroshell that can be hard packed into a small volume for launch and then deployed prior to atmospheric entry for a controlled deceleration through the atmosphere. Large deployable heat shields enable spacecraft to carry bigger, heavier payloads, including scientific instruments and human support systems for planetary landing and exploration. Much larger than traditional fixed diameter aeroshells that are constrained by the size of launch vehicle shrouds, inflatable decelerators create more drag and start the deceleration process in the upper reaches of the atmosphere with greater efficiency and stability. LOFTID’s successful demonstration of the HIAD technology has greatly expanded NASA’s options for future planetary missions and opened new commercial opportunities for lower-cost mission pay-load recovery including recovery of launch vehicle assets, or as a delivery system to return cargo from the International Space Station or cislunar space. The developments for some of these applications are al-ready underway. While LOFTID was indeed a first-of-a-kind flight for an inflatable heatshield, the largest blunt-body entry ever, its remarkable performance assured that it will not be the last of its kind.

John DiNonno↗

High Density Packaging Technologies for RF Electronics in Small Spacecraft

This paper will describe a few high density packaging technologies which we are currently exploring for use in current and future small spacecraft applications. The three categories of technologies include organic multichip modules (MCMs), ceramic leadless surface mount technology (SMT) and 3D printed waveguide structures. There are many other packaging technologies that currently exist but these three were selected in part due to their long heritage in various commercial, military and space applications along with each having a relatively clear path to flight. For each of these technologies, detailed examples will be included in which hardware has been fabricated and tested for use in RF electronics for spacecraft transponders. The organic MCM example will be described in most detail and it utilizes a packaging technology by the name of CoreEZ which is a trademark of i3 Electronics. This MCM has shrunk a portion of our electronics down to 1/8th of its previous area. The CoreEZ technology has been shown to be rad hard beyond a total ionizing dose (TID) of 300kRad and the MCM which was fabricated has gone through thermal cycling and shown to have no degradation in performance. The ceramic leadless package examples include packages from high reliability manufactures by the name of KCB solutions and Barry Industries. In the case of KCB solutions, we have multiple products that will be described including a hermetic ceramic carrier which houses three microwave monolithic integrated circuits (MMICs) along with small discrete components. Finally, we will discuss the results of our search for a 3D printing process that allows us to reduce the cost and volume of our waveguide filters and diplexers for low cost small satellite applications. We have fabricated a few prototypes using direct metal laser sintering (DMLS) and metal coated plastics. Each of these packaging technology discussions will have a brief overview of its current and future use.

Aquirre, Fernando↗

High Density Packaging Technologies for RF Electronics in Small Spacecraft

This paper will describe a few high density packaging technologies which we are currently exploring for use in current and future small spacecraft applications. The three categories of technologies include organic multichip modules (MCMs), ceramic leadless surface mount technology (SMT) and 3D printed waveguide structures. There are many other packaging technologies that currently exist but these three were selected in part due to their long heritage in various commercial, military and space applications along with each having a relatively clear path to flight. For each of these technologies, detailed examples will be included in which hardware has been fabricated and tested for use in RF electronics for spacecraft transponders. The organic MCM example will be described in most detail and it utilizes a packaging technology by the name of CoreEZ which is a trademark of i3 Electronics. This MCM has shrunk a portion of our electronics down to 1/8th of its previous area. The CoreEZ technology has been shown to be rad hard beyond a total ionizing dose (TID) of 300kRad and the MCM which was fabricated has gone through thermal cycling and shown to have no degradation in performance. The ceramic leadless package examples include packages from high reliability manufactures by the name of KCB solutions and Barry Industries. In the case of KCB solutions, we have multiple products that will be described including a hermetic ceramic carrier which houses three microwave monolithic integrated circuits (MMICs) along with small discrete components. Finally, we will discuss the results of our search for a 3D printing process that allows us to reduce the cost and volume of our waveguide filters and diplexers for low cost small satellite applications. We have fabricated a few prototypes using direct metal laser sintering (DMLS) and metal coated plastics. Each of these packaging technology discussions will have a brief overview of its current and future use.

Schatzel, Donald↗

A dissipation-induced superradiant transition in a strontium cavity-QED system

Driven-dissipative many-body systems are ubiquitous in nature and a fundamental resource for quantum technologies. However, they are also complex and hard to model because they cannot be described by the standard tools in equilibrium statistical mechanics. Probing nonequilibrium critical phenomena in pristine setups can illuminate fresh perspectives on these systems. Here, we use an ensemble of cold 88 Sr atoms coupled to a driven high-finesse cavity to study the cooperative resonance fluorescence (CRF) model, a classic driven-dissipative model describing coherently driven dipoles superradiantly emitting light. We observe its nonequilibrium phase diagram characterized by a second-order phase transition. Below a critical drive strength, the atoms quickly reach the so-called superradiant steady state featuring a macroscopic dipole moment; above the critical point, the atoms undergo persistent Rabi-like oscillations. At longer times, spontaneous emission transforms the second-order transition into a discontinuous first-order transition. Our observations pave the way for harnessing robust entangled states and exploring boundary time crystals in driven-dissipative systems.

Science & Technology - Other Topics↗