Low Air Density Research Articles

Clinically-relevant reductions in oxygen partial pressure as possible contributor to cardiovascular benefits of sauna practice

The practice of sauna has been found to have both acute and long-term cardiovascular benefits, which are generally postulated to be a result of thermoregulatory physiological adaptations. Another element of sauna conditions which has been overlooked is that the extremely high absolute water content of air at sauna temperature, even at low relative humidity, results in significantly decreased partial pressure of oxygen. Using the Arden-Buck equation for water-carrying capacity of air along with the barometric formula, it is shown in this hypothesis that typical sauna conditions have an oxygen partial pressure reduction that may be equivalent to significant elevations above sea level. This effect may also be enhanced by lower air density further reducing available oxygen relative to respiratory volume.This paper presents the hypothesis that altitude adaptation may be a contributing factor in the cardiovascular benefits of sauna treatments, suggesting that sauna should be considered as an alternative in instances where intermittent hypoxic training is indicated but not available, and that clinical research into sauna treatment is merited for conditions in which intermittent hypoxic training is known to have applications. The hypothesis could be investigated through pulse oximetry of subjects under sauna conditions and by tracking blood markers of altitude adaptation compared to a control group using steam rooms.

Aeolian saltation over plateau gobi: Field studies in the Zhongzaohuo gobi area, northeastern Tibetan plateau, China

Aeolian sand movement, affected by low air density, exhibits special characteristics. Our understanding of saltation, especially in plateau gobi regions, is limited. Here, we report results of aeolian saltation processes over gobi in the Zhongzaohuo area of the northeastern Tibetan Plateau using high-frequency saltation measurement. The key findings include: (1) In turbulent winds, aeolian sand saltation on plateau gobi occurs intermittently. As the aeolian sand transport activity parameter increases, the threshold wind speed Ut for sand movement decreases exponentially. Concurrently, the threshold wind speed required to move sand particles shows a significant increase, being 49%–68% higher than that in lower altitude gobi regions. (2) The average saltation height zq in plateau gobi ranges from 0.25 to 0.40 m, with a mean value of 0.36 ± 0.04 m, which is approximately 2.3–2.6 times higher than that in lower altitude gobi areas. (3) Sand transport rate in the plateau gobi is significantly reduced, being 57%–94% lower than that in lower altitude gobi areas. This research will deepen our knowledge of how turbulent winds affect aeolian sand movements in plateau gobi regions.

Impact of altitude on the dosage of indoor particulates entering an individual’s small airways

The complexity of indoor particulate exposure intensifies at higher altitudes owing to the increased lung capacity that residents develop to meet the higher oxygen demands. Altitude variations impact atmospheric pressure and alter particulate dynamics in ambient air and the human respiratory tract, complicating particulate inhalation. This study assessed the fraction of PM2.5 and PM10 entering small airways. This assessment covered an altitude range from 400 m above sea level to 3650 m, and an in vitro respiratory tract model was used. The experimental results confirmed that with increasing altitude, the penetration fractions of PM2.5 and PM10 significantly increased from 0.133 ± 0.031 and 0.141 ± 0.045 to 0.404 ± 0.159 and 0.353 ± 0.132, respectively. Additionally, the computational fluid dynamics simulation results revealed that among particles with sizes of 0.1 to 10 µm, the 7.5-μm particles exhibited the most substantial reduction in deposition in the upper airway, displaying a decrease of 6.27%. Our findings underscore the health risks faced by low-altitude residents during acclimatization to higher altitudes, as they experience heightened exposure to particulate matter sources.

Aerodynamic performance study of propellers for Mars atmospheric environment

In terms of flight conditions, the Martian atmospheric environment is undoubtedly much harsher than the Earth atmospheric environment, with extremely low air density, ultra-low Reynolds number, and raging Martian sandstorms, all of which have serious impacts on the design of Martian unmanned aerial vehicles (UAVs), especially for the design of the power system. The purpose of this paper is to study the impact of the Martian atmospheric environment on the aerodynamic performance of the propeller system. The computational fluid dynamics numerical simulation was used to study the impact of varying degrees of sand and dust accumulation on the aerodynamic performance of Martian propellers caused by Martian sandstorms and widespread dust. It was found that in the Martian atmospheric environment, the rough surface of propeller blades after sand and dust accumulation has better aerodynamic performance than the smooth surface, which is greatly different from the Earth environment; The aerodynamic characteristics of the propeller are tested in the simulated Martian atmosphere vacuum chamber environment, and the experiment has shown that the propeller has better aerodynamic performance under the condition of 8° angle of attack; under the condition of 8° angle of attack, the aerodynamic performance of the propeller is simulated by different Reynolds numbers and different Mach numbers, so as to obtain the influence of the Reynolds number and the Mach number on lift–drag characteristics under the Martian atmospheric environment, and then, the modified blead element theory suitable for the Martian atmospheric environment is derived, which provides a detailed reference for the accurate modeling of the Mars UAV. It has important guiding significance for the design of flight controller.

Comparisons of Rainfall Microphysical Characteristics between the Southeastern Tibetan Plateau and Low-Altitude Areas

Abstract The low air pressure and density over the Tibetan Plateau may have an impact on the microphysical features of rainfall. Using a two-dimensional video disdrometer (2DVD), a Micro Rain Radar (MRR), and a microwave radiometer (MWR), the features of the raindrop size distribution (DSD) on the southeastern Tibetan Plateau (SETP) are explored and compared with those in low-altitude regions. The falling speed of raindrops on the SETP is higher than that in low-altitude areas. Under different rainfall-rate categories, the number concentration and the maximum diameter of raindrops on the SETP are smaller than those in low-altitude regions. The convective rainfall on the SETP is more maritime-like because the South Asian summer monsoon brings water vapor from the ocean here. For stratiform and convective rainfall, the SETP has more small-sized raindrops than low-altitude locations. The mass-weighted mean diameters (Dm) on the SETP are the smallest among six sites. The generalized intercept parameter (Nw) of stratiform rainfall is balanced at a low rainfall rate, while that of convective rainfall is balanced at a high rainfall rate. Furthermore, for a given μ (the shape parameter of gamma distribution) value, the λ (the slope parameter of gamma distribution) value on the SETP is the highest of the six sites. Significance Statement For the occurrence and progression of rainfall, microphysical processes (for instance, collision, fragmentation, coalescence, and evaporation) that take place when rainfall particles descend are crucial. A key factor in the microphysical features of rainfall that varies with rainfall rates and types is the raindrop size distribution (DSD). The southeastern Tibetan Plateau (SETP)’s unique terrain ensures that there is enough moisture for rain to fall there, but little is known about the microphysical aspects of this type of precipitation. There has not been enough research done on how the high altitude affects the microphysical features of rainfall. The microphysical features of rainfall in this area must thus be studied.

Numerical Exploration of Transverse Sonic Jet In Hypersonic Cross-flow

At high altitudes, due to low air density, the control response of highly agile and manoeuvrable aerospace vehicles through conventional aerodynamic surfaces is rather slow and inadequate. The control demand of such vehicles can be met very effectively with high-pressure side jets positioned at different locations of the vehicle. Additionally, as none of the components of passive jet control intrudes in the flow path in a passive state, no additional drag is incurred. CFD methods are increasingly being used to characterize jet-controlled aerospace vehicles. Before using in the design exercise, CFD methods need to be validated against reliable experimental results to find its range of applications and error band. In this work, a recent experimental study of transverse sonic injection into Mach 5 hypersonic stream is numerically explored by solving three-dimensional Reynolds Averaged Navier Stokes (RANS) equations using a commercial CFD solver. The computed surface pressures show a reasonable match with experimental results for different momentum ratios of jet and free stream flows. The predictive capabilities of different turbulence models were assessed. The spreading and penetration characteristics of the injectant are analysed from the computed data. The computed penetration and spreading of the injectant depicts nearly linear dependence with the momentum ratio.

Analysis of Aerodynamic Characteristics of Propeller Systems Based on Martian Atmospheric Environment

Compared to detection methods employed by Mars rovers and orbiters, the employment of Mars UAVs presents clear advantages. However, the unique atmospheric conditions on Mars pose significant challenges to the design and operation of such UAVs. One of the primary difficulties lies in the impact of the planet’s low air density on the aerodynamic performance of the UAV’s rotor system. In order to determine the aerodynamic characteristics of the rotor system in the Martian atmospheric environment, a rotor system suitable for the Martian environment was designed under the premise of fully considering the special atmospheric environment of Mars, and the aerodynamic characteristics of the rotor system in the compressible and ultra-low Reynolds number environment were numerically simulated by means of a numerical calculation method. Additionally, a bench experiment was conducted in a vacuum chamber simulating the Martian atmospheric environment, and the aerodynamic characteristics of the UAV rotor system in the Martian environment were analyzed by combining theory and experiments. The feasibility of the rotor system applied to the Martian atmospheric environment was verified, and the first generation of Mars unmanned helicopters was developed and validated via hovering experiments, which thereby yielded crucial data support for the design of subsequent Mars UAV models.

Numerical Investigation on Aerodynamics of a Rectangular Blade Rotor under Mars Air Conditions Using Large Eddy Simulation

The study of the aerodynamics of a flight vehicle under Martian air conditions is experimentally difficult due to its characteristics such as low air density and temperature, making the vehicle operate at an ultra-low Reynolds number, which in turn introduces a complex flow field. In this paper, to find a proper computational fluid dynamics (CFD) method with which to better understand the aerodynamics of rotor-type aircraft under Martian air conditions, the aerodynamic performance of a rotor with rectangular blades under ultra-low density Martian air conditions is studied. A simulation scheme using a large eddy simulation solver and sliding meshing technology is established, and the method is verified based on experimental results from a Mars Air Simulator (MAS). In addition, the influence of the test bench and chamber is investigated through flow field analysis. The results show that the established method can predict lift in a very accurate manner, but that the torque prediction is not so promising. The study also determines that the fixture and the chamber wall of an MAS has little influence on the prediction of aerodynamic performance due to the quickly decreasing of flow speed and dissipation of vortexes. The test bench has about 5% influence on lift prediction, possibly due to the ground effect of the bench. In addition, simulation under actual Martian air conditions shows that the results agree well with the MAS experiment’s results, indicating that the temperature difference has little influence on the lift performance, and therefore that the MAS is a good tool for the lift prediction of Martian helicopters.

Triggering effects of large topography and boundary layer turbulence on convection over the Tibetan Plateau

Abstract. In this study, we analyze the diurnal variations and formation mechanisms of low clouds at different elevations. We further discuss whether there exists a triggering mechanism for convection over the Tibetan Plateau (TP) and whether there is an association among low air density, strong turbulence, and ubiquitous “popcorn-like” cumulus clouds. The buoyancy term (BT) and shear term (ST) over the TP are significantly greater than those at low elevations, which is favorable for the formation of an increasing planetary boundary layer height (PBLH) and also plays a key role in the convective activities in the lower troposphere. From the viewpoint of global effects, the triggering of convection by boundary layer dynamics is analyzed over the TP, but also in the Northern Hemisphere over the Rocky Mountains. It is found that ST and BT are strong over both high-elevation regions. The strong thermal turbulence and large-scale ascending motion jointly result in obvious positive values of PBLH–LCL (lifting condensation level) under low relative humidity (RH) conditions over the TP. The obvious large-scale subsidence on both sides of the Rocky Mountains, especially the western side, leads to inversion above the PBL and lower RH within the PBL, which further leads to negative values of PBLH–LCL and decreased low cloud cover (LCC) in most parts of the Rocky Mountains. The slightly greater-than-zero PBLH–LCL corresponds spatially to increased LCC in the partial regions of the central Rocky Mountains. Thus, less LCC is generated at the Rocky Mountains compared to the TP.

The thermal performance curve for aerobic metabolism of a flying endotherm.

Performance benefits of stable, warm muscles are believed to be important for the evolution of endothermy in mammals, birds and flying insects. However, thermal performance curves have never been measured for a free-flying endotherm, as it is challenging to vary body temperatures of these animals, and maximal flight performance is difficult to elicit. We varied air temperatures and gas densities to manipulate thoracic temperatures of flying honeybees from 29°C to 44°C, with low air densities used to increase flight metabolic rates to maximal values. Honeybees showed a clear thermal performance curve with an optimal temperature of 39°C. Maximal flight metabolic rates increased by approximately 2% per 1°C increase in thoracic temperature at suboptimal thoracic temperatures, but decreased approximately 5% per 1°C increase as the bees continued to heat up. This study provides the first quantification of the maximal metabolic performance benefit of thermoregulation in an endotherm. These data directly support aerobic capacity models for benefits of thermoregulation in honeybees, and suggest that improved aerobic capacity probably contributes to the multiple origins of endothermic heterothermy in bees and other insects.

Diurnal Variation in Cloud and Precipitation Characteristics in Summer over the Tibetan Plateau and Sichuan Basin

The diurnal variation in precipitation and cloud parameters and their influencing factors during summer over the Tibetan Plateau (TP) and Sichuan Basin (SB) were investigated using the Hydro-Estimator satellite rainfall estimates, ground observations, and ERA5 dataset. The precipitation and cloud parameters show diurnal propagation over the SB during the mei-yu period in contrast to such parameters over the TP. The diurnal maximum precipitation from the Hydro-Estimator satellite and cloud ice and liquid water content (cloud LWC and IWC) from the ERA5 dataset are concentrated in the early evening, while their diurnal minimums manifest in the morning. Cloud LWC accounts for more than 60% of the total water during almost the entire diurnal cycle over the inner TP and SB during the mei-yu period. The IWC accounts for more than 60% of the total water in the late afternoon over the edge of the SB and TP. The cloud base height (CBH) above ground level (AGL), the lifting condensation level (LCL) AGL, and the zero degree level AGL are almost equal over the TP during the summer period. The zero degree level AGL over the SB is higher than that over the TP because the air temperature lapse rate over the TP is larger. The thickness of liquid water cloud over the SB is larger than that over the TP. The correlation analysis shows that the CBH AGL and LCL AGL over the TP are related to the dewpoint spread, but less so over the SB because of the stronger turbulence and lower air density over the TP than the SB. Convective available potential energy has a larger impact on precipitation over the TP than the SB. The cloud LWC makes a larger contribution to the precipitation over the SB than over the TP, which is related to the mean zonal wind and diurnal cycle of low-level winds. The precipitation at the edge of the TP and SB (i.e., the steep downstream slope) is largely influenced by the ice water contained within clouds owing to the convergence rising motion over the slopes.

Study on the First-Firing-Cycle combustion characteristics of high-altitude and low-temperature environments during diesel engine cold start

Cold-start performance is one of the main problems that affects the reliability of diesel engines in high-altitude and cold areas. The First-Firing-Cycle (FFC) is the most important cycle during the cold-start process, which apparently affects the cold-start performance. An environmental simulation storehouse and a 3D simulation model were used to study the spray and combustion of FFC in the start-up phase, which temperature varied from −20℃ to 10℃ and altitudes varied from 0 m to 4000 m. A skeleton mechanism using n-dodecane with 117 species and 649 reactions was proposed. Because of the cold temperature and low air density in the plateau area, the cold-start performance was worse and more difficult to reach idle conditions. Verified by experiments and simulations, the spray and combustion characteristics of FFC during the start-up phase were affected by the altitude and ambient temperature obviously. When the altitude increased or the ambient temperature decreased, the atomization and combustion were insufficient, which ultimately produced less power. The control parameters of the Electronic control unit (ECU) should consider the altitude to obtain better cold-start performance in the future.

Rapid Homing Guidance Using Jerk Command and Time-Delay Estimation Method

For certain engagements against small and fast-moving targets at higher altitude, an available total flight time during the terminal homing phase is short due to the limited performance of onboard seekers to detect and track the target, and the autopilot performance of an aerodynamically controlled missile can degrade due to low air density and low dynamic pressure. To increase the lethality of warheads, sometimes terminal zero acceleration, corresponding to zero angle of attack at the instant of interception, is also required. This article proposes a new rapid homing guidance law, which can achieve the terminal zero miss-distance and zero-acceleration response under these severe engagements mentioned earlier. For deriving state feedback form commands that can be implemented to arbitrary order autopilot systems, the polynomial-function-based guidance design method and time-delay estimation method are adopted by introducing a jerk command and more general autopilot dynamics. The characteristics and performance of the proposed guidance law are demonstrated by performing various numerical linear simulations and adjoint simulations, including model uncertainties.

Numerical simulation of particulate matter interaction with the gas diffusion layer of proton‐exchange membrane fuel cells under various relative humidity conditions

Proton-exchange membrane fuel cell (PEMFC) operation and performance degrade when particulate matter (PM) present in the reactant gas stream is collected in the porous structure of the gas diffusion layers (GDL). Interaction of PM carried by the gas stream and their capture efficiency by fibrous structure of GDLs is numerically investigated at various levels of relative humidity (RH) and different particle sizes. For small particles (sub-micron sizes), the Brownian diffusion mechanism is dominant, while transitioning to interception and inertial impaction mechanisms occur as particle size increases (micron sizes or larger). It is found that high humidity levels result in higher diameter and lower density of PM, lower air density, and lower particle bounce due to the absorption of water vapor in the PM. Of these four effects, the first is the most important and the third is the least important. As humidity level is increased, particle capture efficiency decreases for small particles, but increases for large particles. The present study implies that a filter capable of removing large particles must be installed in the upstream reactant gas supply line to avoid the accumulation/clogging of PM in GDL structure.

Construction Characteristics and Quality Control Measures Under High Altitude and Cold Conditions

Restricted by the natural environment factors, the high altitude and cold regions have low air pressure, low air density, large temperature difference between day and night, and long freezing and cold time. During the construction, strict requirements are put forward for the material preparation, material transportation, construction machinery, construction technology, workers’ personal safety and other aspects. Based on the engineering construction in Tibet, this paper studies the optimization scheme of concrete mix proportion and the systematic insulation measures of concrete construction in high altitude and cold regions. The influence of ultra-low temperature on metal welding process is studied. The effects of welding wire selection, welding environment guarantee and worker training on welding quality assurance are studied. The calculation method of mechanical efficiency reduction and the influence of altitude on environmental factors and quota adjustment coefficient are studied. The results of this study provide reference and technical support for the construction in high altitude and cold areas.

Optimal Plate Heat Exchangers of Power Generation Systems

Plate heat exchangers are an effective type of heat exchange equipment and can be used in many power plants. The article analyzes the use of corrugated plate heat exchangers in a number of installations. Their optimization was done according to the economic criterion of optimality, taking into account capital investments and operating costs. The analysis of the plate heat exchangers uses as oil coolers (a number of loads with oil mass flow rates 10….250 kg/s) and water heaters (heat power 100…2000 kW) of steam turbine plants. It has been established that plate oil coolers are more economical than shell-and-tube ones. Also, the anti-icing system plate air heaters of gas turbine plants with a power of 1 to 20 MW considered. The air for the anti-icing system was taken after the compressor and was additionally heated by exhaust gases. It has been established that it is necessary to install an additional flue gas smoke exhauster for using plate heat exchangers. Air must be extracted after the compressor, otherwise, low air density leads to high hydraulic losses, which makes it impossible to use plate heaters. Optimum air velocities are in the range of 0.4…0.6 m/s, flue gas velocities are 4…6 m/s. The use of standard plate heat exchangers with corrugated plates is impractical for GTU powers above 5 MW. Optimization of plate regenerators of supercritical CO2 cycles with recompression for powers from 1 to 15 MW has been done. Optimum velocities of hot CO2 are about 0.8 m/s, cold ones 0.3…0.5 m/s. The optimal sizes of plate heat exchangers are recommended for all of the above applications.

Audible noise spectral characteristics of high‐voltage ac bundled conductors at high altitude

At high altitudes, the corona discharge around a conductor surface is severe, and the induced audible noise (AN) is irritating; this is due to the low air density at high altitudes. Therefore, AN has become a crucial limiting factor in the design of ac power lines of 500 kV or higher at high altitudes. An investigation of the spectral characteristics of AN should help provide a greater understanding of corona noise; however, only a few studies have investigated the spectral characteristics of AN in practical bundled conductors at high altitude. Therefore, it is difficult for power utility companies to select suitable conductors. In this study, the AN spectral characteristics of 6 × LGJ400, 6 × LGJ720, and 8 × LGJ500 bundled conductors were investigated using an ultra-high-voltage corona cage (8 × 8 × 35 m) in Xining, Qinghai Province (altitude: 2261 m). The AN equivalent A-weighted level and the 1/3-octave frequency characteristics of these three conductors were obtained, and the influence of the electric field (E-field) on these characteristics was analysed. Subsequently, the relationship between the AN A-weighted level and the 8-kHz level was examined. We found that, with the increase of the E-field, the low-frequency components of AN level did not exhibit an obvious trend, but in the high-frequency band (1.6–20 kHz), a clear positive correlation was observed between the spectrum level and E-field strength. Among these three conductors, the 8 × LGJ500 conductor was the optimal conductor for reducing the AN levels at high altitude. The results obtained in this study can provide a data reference for the construction of high-altitude ac power lines.

SARS-CoV-2 infection: physiological and environmental gift factors at high altitude.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has emerged as a global pandemic. This viral disease primarily causes lung pneumonia and has a wide range of clinical manifestations. The severity of infection ranges from those who are asymptomatic or with mild symptoms which do not require hospital admission, to those who require ventilator support and eventually die, depending on immunity, age and other comorbidities existing with the patients. The present report is an attempt to study the effect of physiological and environmental factors existing at high altitudes (HA) with spread of SARS-CoV-2 infection. Analysis of existing data revealed that HA natives do possess certain physiological advantages such as (1) improved hypoxic ventilatory response, (2) higher concentration of oxygen carrying molecules, haemoglobin, (3) increased production of Vitamin D, due to intense solar radiation, (4) lower rates of comorbidities such as lung infections, obesity etc. and (5) most importantly reduced production of angiotensin converting enzyme 2, a carrier molecule for SARS-CoV-2 virus entry into the host cell; all of which can collectively account for improved tolerance to SARS-CoV-2 infection in HA natives. In addition, environmental factors at HA such as (6) dry and chilly winds, (7) low air density and (8) intense UV radiations may further inhibit viral growth and spread into the atmosphere. We thus conclude that, high altitude natives may posses physiological and environmental advantage over low landers in terms of reduced severity of SARS-CoV-2 infection and its limited spread.Graphic abstractGift factors associated with COVID-19 spread at high altitude.

Comparative transcriptome analysis reveals regulatory genes involved in cold tolerance and hypoxic adaptation of high-altitude Tibetan bumblebees

China has many habitats supporting a wide diversity of bumblebees, some species of which are limited in distribution to the Tibet Plateau. The high-altitude Tibet Plateau, which has low air density as well as extremely low temperatures, strains the energy requirements for flight in most insects. However, high-altitude bumblebees have adapted to the harsh conditions of this type of habitat. Bumblebees are a particular group of insect pollinators that exclusively utilize carbohydrates from flowers for energy to sustain flight. Here, gene expression was compared between low-altitude species and Bombus longipennis, and the genes upregulated in B. longipennis were involved in aerobic metabolism, such as the oxidative phosphorylation and citric acid cycle (TCA cycle) pathways. Furthermore, a conjoint analysis of the transcriptomes of six bumblebee species from the high-altitude Tibet Plateau and two bumblebee species from the low-altitude North China Plain showed that 19 genes were commonly upregulated in high-altitude species. Among these 19 commonly upregulated genes, Pfk1 was enriched in multiple glycometabolic pathways, which are the main energy pathways in bees; this upregulation enhanced the aerobic and anaerobic glycolysis processes to produce more ATP molecules to supply energy for high-altitude bumblebee flight under severe cold conditions. In addition, glycolysis was enhanced by two other genes, Rac1 and AAC2. Relative quantitative real-time PCR was used to verify that the three genes Pfk1, Rac1, and AAC2 were upregulated in the six main bumblebee species inhabiting the Tibet Plateau.

Vertical α/β-Ga2O3 phase junction nanorods array with graphene-silver nanowire hybrid conductive electrode for high-performance self-powered solar-blind photodetectors

Gallium oxide semiconductor, with a bandgap energy of 4.9 eV, is regarded as a hopeful candidate for next-generation solar-blind photodetectors. However, the construction of photodetector based on Ga2O3 pn junction is still challengeable due to immature doping technology of p-Ga2O3. By considering the small lattice mismatch (＜3%) and similar band gap structure of α-Ga2O3 and β-Ga2O3, a well-designed solar-blind photodetector was built, based on vertical α/β-Ga2O3 junction nanorod arrays (NRAs) with a graphene-silver nanowires (Ag NWs) hybrid top electrode. Thanks to the high conductivity and optical transmittance of graphene-Ag NWs top electrode, the photodetector based on α/β-Ga2O3 junction NARs displayed excellent photoelectric performance. Meanwhile, the matched band structure of Π type formed at the interface of α/β-Ga2O3 junction promoted the automatic separation of photogenerated carriers and their transfer to the corresponding electrodes. A fast photoresponse time of 0.54 s, a high light-to-dark ratio about 2000, and a high rejection ratio (R254/R365) of 2.7 × 103 under the zero bias, were realized. The excellent photoelectrical performance of α/β-Ga2O3 junction photodetector even in vacuum environment forecasts its potential application in some low air density fields, such as missile early warning and tracking and ozone hole monitoring.