Vacuum Conditions Research Articles

Master equation modeling of blackbody infrared radiative dissociation (BIRD) of hydrated peroxycarbonate radical anions.

Molecular cluster ions, which are stored in an electromagnetic trap under ultra-high vacuum conditions, undergo blackbody infrared radiative dissociation (BIRD). This process can be simulated with master equation modeling (MEM), predicting temperature-dependent dissociation rate constants, which are very sensitive to the dissociation energy. We have recently introduced a multiple-well approach for master equation modeling, where several low-lying isomers are taken into account. Here, we experimentally measure the BIRD of CO4●-(H2O)1,2 and model the results with a slightly modified multiple-well MEM. In the experiment, we exclusively observe loss of water from CO4●-(H2O), while the BIRD of CO4●-(H2O)2 leads predominantly to loss of carbon dioxide, with water loss occurring to a lesser extent. The MEM of two competing reactions requires empirical scaling factors for infrared intensities and the sum of states of the loose transition states employed in the calculation of unimolecular rate constants so that the simulated branching ratio matches the experiment. The experimentally derived binding energies are ΔH0(CO4●--H2O) = 45 ± 3kJ/mol, ΔH0(CO4●-(H2O)-H2O) = 41 ± 3kJ/mol, and ΔH0(CO2-O2●-(H2O)2) = 37 ± 3kJ/mol. Quantum chemical calculations on the CCSD(T)/aug-cc-pVTZ//CCSD/aug-cc-pVDZ level, corrected for the basis set superposition error, yield binding energies that are 2-5kJ/mol higher than experiment, within error limits of both experiment and theory. The relative activation energies for the two competing loss channels are as well fully consistent with theory.

A study of morphological, optical, and photoluminescence properties of ZnS thin films doped Mn and ca

In this study, zinc sulfide (ZnS) thin films were deposited via physical vapor deposition (PVD) under high vacuum conditions, incorporating dual dopants manganese (Mn2+) and calcium (Ca2+). Morphological examination by AFM revealed that Mn2+ promoted a uniform and smooth film structure, whereas Ca2+ induced surface roughness. Optical characterization using ultraviolet–visible spectroscopy showed high transparency in the visible range, with doping leading to significant alterations in the bandgap energy. Photoluminescence investigations displayed prominent emission peaks at 385 nm, 448 nm, and 560 nm, characteristic of ZnS bandgap emissions, as well as an additional peak at 600 nm due to the novel dopant's influence. X-ray fluorescence (XRF) and Fourier transform infrared (FTIR) analyses verified the presence of ZnS and other constituents. Doping improved the optical and luminescent characteristics, offering potential for use in optoelectronics, light-emitting diodes (LEDs), and advanced technology development. This customizable approach to ZnS thin films presents innovative opportunities within material science and device manufacturing.

Ti compound coating of carbonyl iron particles with controlled surface conditions using a peroxotitanium acid solution for stable magnetic particles

The surface coating of carbonyl iron particles (CIPs) deposited under various surface conditions was examined using a peroxotitanium acid (PTA) solution including H2O2 to obtain highly stable magnetic particles. Upon adsorption on the CIP surfaces, peroxotitanium complexes dehydrated and transformed into TiO2 with hydroxides (TiO2–OH), and the coating morphology significantly changed depending on the surface conditions of the CIPs. The volatile surface impurities that remained on raw CIPs inhibited the adsorption of the complexes, leading to insufficient coating. As oxidation treatment using a boric acid aqueous solution was performed to examine the effects of surface oxides on the coating, the treatment increased the oxide layer thickness and specific surface area of the raw CIPs. During the coating of oxidized CIPs, active surfaces were dissolved in a PTA solution, and γ-FeOOH plate particles were redeposited on the particle surfaces because H2O2 remaining in the PTA solution initially oxidized the active surfaces and then depleted. The results indicated that the treatment with the PTA solution was not suitable for oxidized CIPs with increased specific surface area. A simple dry treatment under vacuum conditions decreased surface impurities on raw CIPs without increasing their specific surface area; consequently, their surfaces were uniformly and sufficiently coated with TiO2–OH. The uniform surface coating decreased the saturation magnetization of the CIPs by only 0.98% and improved their oxidation onset temperature from 369.8°C to 437.1°C, making them suitable for practical use.

Lyophilization for bacteria preservation: a promising approach for Yersinia pestis strains from an unique collection in Brazil (Fiocruz-CYP).

Yersinia pestis, the causative agent of plague, is a highly virulent bacterium that poses a significant threat to human health. Preserving this bacterium in a viable state is crucial for research and diagnostic purposes. This paper presents and evaluates a simple lyophilization protocol for the long-term storage of Y. pestis strains from Fiocruz-CYP, aiming to explore its impact on viability and long-term stability, while replacing the currently used methodologies. The lyophilization tests were conducted using the non-virulent Y. pestis strain EV76, subjected to the lyophilization process under vacuum conditions. Viability assessment was performed to evaluate the effects of lyophilization and storage conditions on Y. pestis under multiple temperature conditions (- 80°C, - 20°C, 4-8°C and room temperature). The lyophilization protocol employed in this study consistently demonstrated its efficacy in maintaining high viability rates for Y. pestis samples in a up to one year follow-up. The storage temperature that consistently exhibited the highest recovery rates was - 80°C, followed by - 20°C and 4-8°C. Microscopic analysis of the post-lyophilized cultures revealed preserved morphological features, consistent with viable bacteria. The high viability rates observed in the preserved samples indicate the successful preservation of Y. pestis using this protocol. Overall, the presented lyophilization protocol provides a valuable tool for the long-term storage of Y. pestis, offering stability, viability, and functionality. By refining the currently used methods of lyophilization, this protocol can improve long-term preservation for Y. pestis strains collections, facilitating research efforts, diagnostic procedures, and the development of preventive and therapeutic strategies against plague.

Unveiling of novel synthesized coumarin derivative for efficient self-driven hybrid organic/inorganic photodetector applications

During this study, a novel organic semiconductor material comprising coumarin and chromone moieties was synthesized via a facile route. Thin films of the synthesized powder were thermally deposited under vacuum conditions. The structural and morphological properties were investigated using X-ray diffraction and scanning electron microscope techniques, respectively. With increasing the film thickness, a relative crystallinity enhancement was observed, besides improving the surface features and uniformity. Furthermore, the UV–vis–NIR spectral transmittance and reflectance of the grown films were measured. The variation of film thickness induced significant changes in the optical parameters either dispersive or electronic such as energy gap (3.67–3.8 eV), oscillator energy (4.25–4.56 eV), and dispersion energy (4.61–10.31 eV). In addition, the nonlinear optical parameters and PL emission spectra of the prepared films were measured and analyzed in detail. Then, these films were exploited integrally with p-Si for the fabrication hybrid junction for light sensing. The optimized film thickness based on the optical, structure results, and electronic performance under dark conditions was ∼124 nm. Such a device showed a pronounced self-driven photodetection performance under different illumination intensities. The photoelectronic parameters including responsivity (∼5.17 mA/W), detectivity (∼2.64 × 1010 Jones), linearity (∼72.72 dB), and rise/fall times(∼51.48 ms/47.75 ms) were extracted and compared to other organic/p-Si devices and showed a high superiority.

On-Demand Bioactivation of Inert Materials With Plasma-Polymerized Nanoparticles.

Conventional gas plasma treatments are crucial for functionalizing materials in biomedical applications, but have limitations hindering their broader use. These methods require exposure to reactive media under vacuum conditions, rendering them unsuitable for substrates that demand aqueous environments, such as proteins and hydrogels. In addition, complex geometries are difficult to treat, necessitating extensive customization for each material and shape. To address these constraints, an innovative approach employing plasma polymer nanoparticles (PPN) as a versatile functionalization tool is proposed. PPN share similarities with traditional plasma polymer coatings (PPC) but offer unique advantages: compatibility with aqueous systems, the ability to modify complex geometries, and availability as off-the-shelf products. Robust immobilization of PPN on various substrates, including synthetic polymers, proteins, and complex hydrogel structures is demonstrated in this study. This results in substantial improvements in surface hydrophilicity. Materials functionalization with arginylglycylaspartic acid (RGD)-loaded PPN significantly enhances cell attachment, spreading, and substrate coverage on inert scaffolds compared to passive RGD coatings. Improved adhesion to complex geometries and subsequent differentiation following growth factor exposure is also demonstrated. This research introduces a novel substrate functionalization approach that mimics the outcomes of plasma coating technology but vastly expands its applicability, promising advancements in biomedical materials and devices.

Efficient and Selective Removal of Palladium from Simulated High-Level Liquid Waste Using a Silica-Based Adsorbent NTAamide(C8)/SiO2-P.

In order to realize the effective separation of palladium from high-level liquid waste (HLLW), a ligand-supported adsorbent (NTAamide(C8)/SiO2-P) was prepared by the impregnation method in a vacuum. The SiO2-P carrier was synthesized by in situ polymerization of divinylbenzene and styrene monomers on a macroporous silica skeleton. The NTAamide(C8)/SiO2-P adsorbent was fabricated by impregnating an NTAamide(C8) ligand into the pore of a SiO2-P carrier under a vacuum condition. The adsorption performance of NTAamide(C8)/SiO2-P in nitric acid medium has been systematically studied. In a solution of 0.2 M HNO3, the distribution coefficient of Pd on NTAamide(C8)/SiO2-P was 1848 mL/g with an adsorption percentage of 90.24%. With the concentration of nitric acid increasing, the adsorption capacity of NTAamide(C8)/SiO2-P decreases. Compared to the other 10 potential interfering ions in fission products, NTAamide(C8)/SiO2-P exhibited excellent adsorption selectivity for Pd(II). The separation factor (SFPd/other metals > 77.8) is significantly higher than that of similar materials. The interference of NaNO3 had a negligible effect on the adsorption performance of NTAamide(C8)/SiO2-P, which maintained above 90%. The adsorption kinetics of Pd(II) adsorption on NTAamide(C8)/SiO2-P fits well with the pseudo-second order model. The Sips model is more suitable than the Langmuir and Freundlich model for describing the adsorption behavior. Thermodynamic analysis showed that the adsorption of Pd(II) on NTAamide(C8)/SiO2-P was a spontaneous, endothermic, and rapid process. NTAamide(C8)/SiO2-P also demonstrated good reusability and economic feasibility.

Landsat 9 Thermal Infrared Sensor-2 (TIRS-2) Pre- and Post-Launch Spatial Response Performance

The launch of Landsat 9 (L9) on 27 September 2021 marks the ongoing commitment of the Landsat mission to delivering users with calibrated Earth observations for fifty years. The two imaging sensors on L9 are the Thermal Infrared Sensor-2 (TIRS-2) and the Operational Land Imager-2 (OLI-2). Shortly after launch, the image data from OLI-2 and TIRS-2 were evaluated for both radiometric and geometric quality. This paper provides a synopsis of the evaluation of the spatial response of the TIRS-2 instrument. The assessment focuses on determining the instrument’s ability to detect a perfect knife edge. The spatial response was evaluated both pre- and post-launch. Pre-launch testing was performed at NASA Goddard Space Flight Center (GSFC) under flight-like thermal vacuum (TVAC) conditions. On orbit, coastline targets were identified to evaluate the spatial response and compared against Landsat 8 (L8). The pre-launch results indicate that the spatial response of the TIRS-2 sensor is consistent with its predecessor on board L8, with no noticeable decline in image quality to compromise any TIRS science objectives. Similarly, the post-launch analysis shows no apparent degradation of the TIRS-2 focus during the launch and the initial operational timeframe.

Synthesizing lunar regolith-geopolymer emulating lunar positive temperature regime

The development of lunar habitat using lunar regolith is a captivating research area for constructing lunar bases, especially after the discovery of polar ice, and molecular water on the lunar south pole. The aim of this research is to synthesize a robust lunar regolith geopolymer by fine-tuning the concentration and ratios of alkaline activators while implementing curing under lunar positive thermal regime. The geopolymer was synthesized containing lunar highlands simulant (LHS-1) and mare regolith simulant (LMS-1) at the lowest water content using sodium (Na) and potassium (K) based alkaline activators emulating positive temperature regime collected by Diviner Lunar Radiometer Experiment (DLRE). The maximum compressive strength of 41.23 MPa was achieved for highlands regolith simulant-based geopolymer containing a Na-activator with the lowest water-to-precursor ratio of 0.23. The surplus alkali cations in the geopolymer paste matrix resulted in the formation of carbonation products after reacting with atmospheric carbon dioxide. K-activator geopolymer resulted in Kalicinite which has lower thermal stability and dissolution in water, whereas sodium carbonate formed in Na-activator-based geopolymer engrained and embedded precursor particles alongside sodium-calcium aluminosilicate hydrate (N-(C)-A-S-H) gel forming more densified microstructure. Conclusively, lunar regolith geopolymer has the potential for the construction of lunar habitat. However, this study recommends synthesizing geopolymer in vacuum conditions, emulating freeze-thaw cycles for a more precise estimation of microstructural developments and evaluating other critical properties.

SERS analysis, DFT, and solution effects regarding the structural and optical characteristics of folic acid biomolecule adsorbed on a Cu3 metal cluster

The optical characteristics of folic acid (ABP) and metal clusters of copper (Cu3) at various locations were investigated by means of density functional theory (DFT) computations. Mulliken charge analysis and molecular electrostatic potential (MEP) surface show how charge moves from Cu3 to ABP through the various groups. The peak in the UV–Vis spectra of ABP-Cu3 is caused by bonding and anti-bonding orbitals. In both vacuum and aqueous conditions, the polarizability values of ABP-Cu3 cluster are significantly higher than those of pure ABP, indicating a possible enhancement of the nonlinear optical (NLO) effect. Our research investigates the possibility of using ABP adsorbed metal clusters for NLO materials. Surface enhanced Raman scattering (SERS) in the ABP adsorbed metal clusters enhances the vibrational modes of ABP. Adsorption energies are found to be in the range −17.08 to −58.52 kcal/mol in vacuum and −53.34 to −93.44 kcal/mol in aqueous medium for the different configurations for ABP-Cu3. It indicates that metal clusters adsorbed by ABP are stable in the aqueous media. Experimental IR and UV–Vis of ABP is in agreement with theoretically predicted ones.

Onset of Nitriles Hydration with an Environmentally Benign Catalyst: in-Water versus on-Water Conditions.

The reaction yield of nitriles hydration using a catalyst depends on the aqueous medium. Using ab initio molecular dynamics, we probed whether "in-water" (in bulk medium) or "on-water" (at the interface with vacuum) conditions can change the onset of the reaction. Investigating a hydrogen-bond mediated mechanism, the lifetimes of the intermolecular interaction between benzonitrile and choline in the two protocols were compared, and the diffusion of the hydroxide anion around the cyano group was discussed.

Design and characterization of an antiproton deceleration beamline for the PUMA experiment

We report on the design and characterization of an antiproton deceleration beamline, based on a pulsed drift tube, for the PUMA experiment at the Antimatter Factory at CERN. The design has been tailored to high-voltage (100kV) and ultra-high vacuum (below 10−10mbar) conditions. A first operation achieved decelerating antiprotons from an initial energy of 100keV down to (3898±3)eV, marking the initial stage in trapping antiprotons for the PUMA experiment. Employing a high-voltage ramping scheme, the pressure remains below 2×10−10mbar upstream of the pulsed drift tube for 75% of the cycle time. The beamline reached a transmission of (55±3)% for antiprotons decelerated to 4keV. The beam is focused on a position sensitive detector to a spot with horizontal and vertical standard deviations of σhoriz=(3.0±0.1)mm and σvert=(3.8±0.2)mm, respectively. This spot size is within the acceptance of the PUMA Penning trap.

Air-based sputtering deposition of TiN(O)/a-TiNxOy multilayer films for enhanced mechanical properties and corrosion resistance

Extensive research has explored multilayer films for their distinctive mechanical and functional properties. This study employs an air-based sputtering technique, using air as a reactive gas under low vacuum conditions, to produce TiN(O)/a-TiNxOy multilayer films. By alternately adjusting the air/Ar flow ratios, the multilayer films with various modulation periods were created. The crystalline TiN(O)/amorphous TiNxOy multilayered structure was confirmed via cross-sectional microscopy and electron energy loss spectroscopy images and mappings. Hardness (H) and elastic modulus (E) initially increased, peaked, and then decreased with the modulation period, reaching a maximum hardness of 31.2 GPa and an elastic modulus of 343 GPa. The enhancements may be attributed to internal compressive stress, interface strain effects, and the inhibition of dislocation propagation throughout the films. Higher H/E ratios (0.09–0.11) and H3/E2 ratios (0.23–0.28 GPa) suggest enhanced resistance to elastic and plastic deformation, surpassing those of single-layered TiN(O). This enhancement is primarily attributed to the hard/soft multilayer design. Potentiodynamic polarization tests revealed improved corrosion resistance with decreasing modulation period, reaching optimal values Ecorr at −0.089 V and Icorr at 0.272 μA/cm2. This improvement is mainly ascribed to the multilayer design, which inhibits direct corrosion through grain boundaries. This air-based sputtering technique offers a facile approach for producing complex multilayer films, promising enhanced mechanical properties and corrosion resistance of coatings for various applications.

Mass Inversion at the Lifshitz Transition in Monolayer Graphene by Diffusive, High-Density, On-Chip Doping.

Experimental setups for charge transport measurements are typically not compatible with the ultrahigh vacuum conditions for chemical doping, limiting the charge carrier density that can be investigated by transport methods. Field-effect methods, including dielectric gating and ionic liquid gating, achieve too low a carrier density to induce electronic phase transitions. To bridge this gap, we developed an integrated flip-chip method to dope graphene by alkali vapor in the diffusive regime, suitable for charge transport measurements at ultrahigh charge carrier density. We introduce a cesium droplet into a sealed cavity filled with inert gas to dope a monolayer graphene sample by the process of cesium atom diffusion, adsorption, and ionization at the graphene surface, with doping beyond an electron density of 4.7 × 1014 cm-2 monitored by operando Hall measurement. The sealed assembly is stable against oxidation, enabling measurement of charge transport versus temperature and magnetic field. Cyclotron mass inversion is observed via the Hall effect, indicative of the change in Fermi surface geometry associated with the Liftshitz transition at the hyperbolic M point of monolayer graphene. The transparent quartz substrate also functions as an optical window, enabling nonresonant Raman scattering. Our findings show that chemical doping, hitherto restricted to ultrahigh vacuum, can be applied in a diffusive regime at ambient pressure in an inert gas environment and thus enable charge transport studies in standard cryogenic environments.

Microstructure and mechanical properties of high relative density Ti-48Al-1Fe alloy using irregular blend powder

Conventional pressing and sintering methods provide difficulties in achieving high density for PM TiAl alloys. The Ti-48Al-1Fe alloy was prepared via vacuum pressure-less sintering, and the microstructure evolution and mechanical properties during the sintering densification process of the mixed powder system were investigated. The results shows that the density of the mixed powder reached 98.3 ± 0.14% after pressure-less sintering for 3 hours under high vacuum conditions at 1300°C. The microstructure of the as-sintered alloy is a fine duplex structure composed of α2/γ lamellar colonies and the composite structure. The ultimate tensile strength (UTS) of the as-sintered alloy at room temperature is 315 MPa. The density of the as-sintered alloy reach more than 99.9% after non-capsule hot isostatic pressing (HIP). The as-HIPed alloy exhibits an UTS of 332 MPa at room temperature. At high temperatures, it maintains high strength, with an UTS of 408 MPa and yield strength of 386 MPa at 900°C, which is comparable to that of forged TiAl alloy. Furthermore, the elongation of the sample at 900°C is 20.0%. This process offers a novel method for sintering PM TiAl with high density and mechanical properties at a low cost and near-net shape.

The Norbornadiene/Quadricyclane Pair as Molecular Solar Thermal Energy Storage System: Surface Science Investigations.

For the transition to renewable energy sources, novel energy storage materials are more important than ever. This review addresses so-called molecular solar thermal (MOST) systems, which appear very promising since they combine light harvesting and energy storing in one-photon one-molecule processes. The focus is on norbornadiene (NBD), a particularly interesting candidate, which is converted to the strained valence isomer quadricyclane (QC) upon irradiation. The stored energy can be released on demand. The energy-releasing cycloreversion from QC to NBD can be initiated by a thermal, catalytic, or electrochemical trigger. The reversibility of the energy storage and release cycles determines the general practicality of a MOST system. In the search for derivatives, which enable large-scale applications, fundamental surface science studies help to assess the feasibility of potential substituted NBD/QC couples. We include investigations under well-defined ultra-high vacuum (UHV) conditions as well as experiments in liquid phase. Next to the influence of the catalytically active surfaces on the isomerization between the two valence isomers, information on adsorption geometries, thermal stability limits, and reaction pathways of the respective molecules are discussed. Moreover, laboratory-scaled test devices demonstrate the proof of concept in various areas of application.

Stability and Electronic Structure of Nitrogen-Doped Graphene-Supported Cun (n = 1-5) Clusters in Vacuum and under Electrochemical Conditions: Toward Sensor and Catalyst Design.

Here, we present a detailed computational study of the stability and the electronic structure of nitrogen-doped graphene (N4V2) supported Cun (n = 1-5) clusters, which are promising carbon-dioxide electroreduction catalysts. The binding of the clusters to the nitrogen-doped graphene and the electronic structure of these systems were investigated under vacuum and electrochemical conditions. The stability analysis showed that among the systems, the nitrogen-doped graphene bound Cu4 is the most stable in vacuum, while in an electrolyte, and at a negative potential, the N4V2-Cu3 is energetically more favorable. The ground state electronic structure of the nitrogen-doped graphene substrate undergoes topological phase transition, from a semimetallic state, and we observed a metallic and topologically trivial state after the clusters are deposited. The electrode potential adjusts the type and density of the charge carriers in the semimetallic models, while the structures containing copper exhibit bands which are deformed and relaxed by the modified number of electrons.

Effect of B2O3 addition to Magnesium, Zirconium, Hafnium fluorides on the parameters of thin films formed from them

For the first time, the influence of a B2O3 additive on Magnesium, Zirconium, and Hafnium fluorides, encompassing their structural and optical properties, was subjected to investigation. The phase composition of the MgF2–B2O3 system was ascertained through the utilization of X-ray phase analysis and infrared (IR) transmission spectroscopy. Notably, a discernible presence of a newly formed phase, characterized as a complex compound of Magnesium fluoroborate (Mg3(BO3)F3), was unveiled. In the instances of the ZrF4–B2O3 and HfF4–B2O3 systems, the modification in the characteristics of IR spectra was attributed to the α → β phase transitions occurring within the respective metal tetrafluorides. Subsequently, thin-film coatings of metal fluorides treated with the B2O3 additive were fabricated employing thermal evaporation under vacuum conditions. It was determined that the refractive index of MgF2 experienced a slight reduction (from 1.42 to 1.41) following the incorporation of the additive, while the mechanical strength exhibited a marginal augmentation. Conversely, the refractive index of coatings derived from Zirconium and Hafnium tetrafluorides, subsequent to heat treatment with B2O3, remained nearly constant at 1.53 across all samples. Additionally, an evaluation of the volatility of the samples was carried out, revealing a slight increase in volatility following treatment with the B2O3 additive, with the exception of the MgF2–B2O3 system. A plausible mechanism elucidating the influence of B2O3 on oxygen-containing impurities present in metal fluorides is proposed.

Switching of n- and p-type doping with partial pressure of oxygen gas on few layers MoS2-field effect transistor

We examined the oxygen adsorption effect on the electric property of the field-effect transistor with an atomic layer MoS2 channel, whose experiment was executed in well-defined ultra-high vacuum conditions and with surface treatment. The threshold voltage change of the Id-Vg curve with the oxygen partial pressure shows n-type doping in the low-pressure range and p-type doping in the high-pressure range. In this report, the Vth vs. oxygen partial pressure uptake curve is well modeled with the Langmuir type adsorption/desorption. The deduced adsorption energy indicates that the adsorbed species are oxygen atoms on the pristine MoS2, suggesting a catalytic behavior of MoS2 for the oxygen reduction reaction. The oxygen adsorption at the S vacant site induces the initial n-type doping. DFT calculation illustrates that, despite the electron transfer from the substrate to the oxygen molecule, the electronic structure change causes the n-type doping.

High-parameters experimental linear plasma device for fusion wall conditioning studies

In future, HELPD would provide valuable platform for investigating the issue in the W impurity control, towards the wall conditioning requirements in tokamak.The tungsten (W) impurity caused by sputtering of the first wall is considered as an issue influencing the plasma safe operation of EAST, ITER and other future fusion devices. As a supplement to the experiments on the tokamak, the linear plasma device (LPD) serves as an effective divertor simulator for the W impurity control research. This work presents the design and construction of High-parameters Experimental Linear Plasma Device (HELPD) in detail, including its layout and operation parameters. Besides the function of plasma exposure, the target sample could be exchanged in a separate material pretreatment vessel for wall conditioning, such as lithium coating and glow discharge cleaning (GDC) without breaking vacuum conditions. And the preliminary results show that the device could produce a steady state plasma of 1∼10 eV, and its flux could reach 1022 m−2s−1 with 10 kW helicon wave. In the future, HELPD would provide valuable platform for investigating the issue in the W impurity control，towards the wall conditioning requirements in tokamak.