Beam Injection Research Articles

Status and analysis perspectives of ICARUS at the Fermilab Short Baseline Neutrino program

After a successful three-year physics run underground at the LNGS in Italy and a significant detector overhaul at CERN, the ICARUS-T600 detector was installed at Fermilab. In 2020, the cryogenic commissioning began with detector cool down, liquid argon filling and recirculation. ICARUS then started its operation collecting the first neutrino events from the Booster Neutrino Beam (BNB) and the Neutrinos at the Main Injector (NuMI) beam off-axis, which were used to test the ICARUS event selection, reconstruction and analysis algorithms. ICARUS successfully completed its commissioning phase in June 2022, and started data taking for neutrino oscillation physics, aiming at first to either confirm or refute the claim by Neutrino-4 short-baseline reactor experiment. ICARUS will also perform measurements of neutrino cross-sections with the NuMI beam and several Beyond Standard Model searches. After the first year of operations, ICARUS will jointly search for evidence of sterile neutrinos with the Short-Baseline Near Detector (SBND), within the Fermilab Short-Baseline Neutrino (SBN) program. In this paper, preliminary technical results from the ICARUS data with the BNB and NuMI beams are presented to highlight the performance of all ICARUS subsystems and its capability to select and reconstruct neutrino events.

The scoping, design, and plasma physics optimization of the Eos neutron source stellarator

Abstract On the path to a fusion pilot plant, Thea Energy plans to build Eos, a sub-breakeven, deuterium-deuterium, beam-target fusion, stellarator neutron source facility for producing tritium and other valuable radioisotopes. In this paper, a set of 1D plasma physics models are coupled and used to design the operating point of the facility and predict performance. At this foundational stage of the design, analytic and approximate models are sufficient to capture the leading-order effects, and fast enough to run in the inner loop of an optimizer. Higher-fidelity analyses will follow. Models of 1D profile-dependent neutral beam stopping, ion beam slowing down, beam-target fusion, electron-ion classical heat transfer, energy confinement (ISS04), beam pressure, beam heating of ions and electrons, beam-beam fusion fraction, and neutral beam injection and gyrotron heating electrical efficiencies are included. A numerical optimizer is used to determine the minimum required facility electric power to generate tritium at a given rate. A potentially advantageous regime is described in which modern precisely-quasisymmetric stellarators, new high-temperature superconductors, ITER-derived neutral beam injection, and new high-frequency gyrotrons enable a suitible target plasma with hot electrons, cold ions, peaked density and temperature profiles, and high beam-injected ion density. It appears possible at this time for a facility with a medium-scale and medium-strength stellarator whose required facility electric power is less than 40 MW to produce 2.5 × 10 17 neutrons s−1 for the production of radioisotopes. With the addition of a tritium breeding blanket, such a facility could produce 0.2 grams d−1 or 70 grams yr−1 of tritium.

High-Voltage Pulsed Power Generator for Beam Injection Systems

Beam injection systems in hadron colliders require kickers generating ±50 kV peak voltages into a 50 Ω impedance, with peak currents of 1000 A and sub-10 ns rise and fall times. This paper presents a novel high-voltage pulse power generator utilizing a distributed pulser architecture. It combines gallium nitride (GaN) transistors in a Marx topology with an inductive adder, achieving nanosecond-scale switching speeds and high-power efficiency. Compared to other solutions such as based on MOSFETs or fast ionization dynistors, our development offers superior peak and average power performance, reduced system complexity, and enhanced reliability, marking a significant step forward in high-voltage pulse generation for accelerator applications.

ITER NBI operational window and power availability constraints due to shine-through losses

Abstract This paper explores the operational boundaries and power availability of the neutral beam injection (NBI) system in ITER, with a specific focus on shine-through loss prevention. Shine-through, a phenomenon where part of the injected neutral beam remains un-ionized in the plasma and directly impacts the first wall components, poses a significant risk to the lifetime of ITER’s plasma-facing components. The operational window for NBI is consequently constrained by these losses, which are influenced by factors such as plasma density, beam energy, and injection geometry. Leveraging advanced numerical simulations, we investigate these dependencies across various ITER plasma scenarios, particularly for the DT-1 phase, which will mark the first NBI operations. In light of recent ITER blanket design changes, our analysis refines previous estimates of the maximum acceptable shine-through power on plasma-facing components. We then present a new heuristic formula which permits the calculation of the shine-through fraction and the minimum plasma density that permits ITER NBI operations as a function of global variables. This allows for establishing operational limits for Hydrogen and Deuterium NBI in Hydrogen, Deuterium, and Deuterium-Tritium plasmas. Additionally, we compare commonly used beam ionisation codes for ITER and tokamak simulations, evaluating their reliability in the investigated parameter space. The findings of this study are crucial for ensuring the efficient operation of the NBI system during ITER's experimental phases. They define the conditions under which beam power can be fully utilised without compromising operational lifetime, thereby informing future plasma operation plans and contributing to the success of ITER's scientific objectives.

Physics design of current drive and strategy of heating system for EHL-2 spherical torus

Abstract ENN He Long-2 (EHL-2) is the next-generation large Mega-Ampere (MA) spherical torus (ST) proposed and funded by ENN company. The design parameters are: Ti0 > 30 keV, ne0~1×1020 m-3, Ip ~ 3 MA, Bt ~ 3 T. How to achieve several MA current flat-top with limited voltage-second (Vs) of center solenoid (CS) coils is one of the most challenges issue of EHL-2. In order to minimize the consumption of Vs, fully non-inductive start-up by ECRH will be applied in EHL-2. The ramp-up phase will be accomplished with the synergetic mode between CS and non-inductive methods. The strategy of non-inductive start-up and ramp-up with synergetic mode has been verified on EXL-50U’s experiments. Based on this strategy, numerical simulations give the feasibility of EHL-2 to achieve 3 MA plasma current. A high-performance steady-state scenario with Ip ~ 1.5 MA is also designed. In this scenario, the bootstrap current fraction fBS > 70%, the safety factor q at the magnetic axis q0 > 2, the minimum safety factor qmin > 1, the poloidal beta β p > 3 and normalized beta β N > 2.3. Each design iteration integrates the validation of physical models with the constraints of engineering implementation, gradually optimizing the performance of the Heating and Current Drive (H&CD) systems. Numerical simulation results for general auxiliary H&CD systems such as neutral beam injection, electron cyclotron wave, ion cyclotron wave, and lower hybrid wave are presented. These simulation results ensure that the 31 MW H&CD systems comprehensively cover all scenarios while maintaining engineering feasibility

Effect of energetic ions on edge-localized modes in tokamak plasmas

The most efficient and promising operational regime for the International Thermonuclear Experimental Reactor tokamak is the high-confinement mode. In this regime, however, periodic relaxations of the plasma edge can occur. These edge-localized modes pose a threat to the integrity of the fusion device. Here we reveal the strong impact of energetic ions on the spatio-temporal structure of edge-localized modes in tokamaks using nonlinear hybrid kinetic–magnetohydrodynamic simulations. A resonant interaction between the fast ions at the plasma edge and the electromagnetic perturbations from the edge-localized mode leads to an energy and momentum exchange. Energetic ions modify, for example, the amplitude, frequency spectrum and crash timing of edge-localized modes. The simulations reproduce some observations that feature abrupt and large edge-localized mode crashes. The results indicate that, in the International Thermonuclear Experimental Reactor, a strong interaction between the fusion-born alpha particles and ions from neutral beam injection, a main heating and fast particle source, is expected with predicted edge-localized mode perturbations. This work advances the understanding of the physics underlying edge-localized mode crashes in the presence of energetic particles and highlights the importance of including energetic ion kinetic effects in the optimization of edge-localized mode control techniques and regimes that are free of such modes.

Characterization of the upgraded photoinjector at the Chinese Academy of Engineering Physics Terahertz Free Electron Laser Facility.

The Chinese Academy of Engineering Physics Terahertz Free Electron Laser Facility (CAEP THz FEL, CTFEL) has been operated as a user facility for over five years. To further meet the growing demands of modern science, an upgrade project for an infrared-terahertz free electron laser facility based on CTFEL has been proposed to broaden the frequency range from 0.1-4.2 to 0.1-125THz. Recently we upgraded the CTFEL photoinjector in order to fulfill the beam injection requirements of the infrared-terahertz free electron laser facility. In this paper, we measured the beam parameters of the upgraded CTFEL photoinjector. A Michelson interferometer was constructed to measure the auto-correlation of the coherent transition radiation emitted by the electron bunch. Both the Kramers-Kronig reconstruction method and the time-domain fitting approach have been employed to estimate the bunch length, resulting in a root-mean-square bunch length of 0.30ps. A normalized transverse emittance of 5.62 π mm mrad was determined by a quadrupole scan. The measured mean energy of the electron bunch is adjustable between 6 and 8MeV with an energy spread of less than 0.5%. These measurements prove that the upgraded CTFEL photoinjector fulfills the injection requirements of the facility to be built.

Simulation of β-induced Alfvén eigenmode instabilities and mode transition for HL-3 hybrid scenario

Abstract Kinetic-magnetohydrodynamic hybrid simulation is performed to investigate the Alfvén eigenmode (AE) and fishbone/fishbone-like instabilities excited by neutral beam injection (NBI) deposited energetic particles (EPs) for HL-3 hybrid scenario. The hybrid scenario is characterized by a flat q-profile in the core due to off-axis electron cyclotron current drive (ECCD). Nonlinear simulation with multiple toroidal mode numbers indicates that the n=2 β-induced AE (BAE) is excited initially in the linear stage and the n=1 fishbone has the highest nonlinear saturation level. EP distribution is modified only slightly in both real and velocity space from its initial state because of a narrow mode structure near the axis. Focusing on the n=2 mode, sensitivity analysis indicates that mode activity and transition depend on the EP pressure, injected energy and q-profile. The dominant unstable mode deviates from fishbone-like mode to BAE by raising EP pressure, and from BAE to toroidicity-induced AE (TAE) by raising NBI injected energy. The mechanism is interpreted through resonant condition and corresponding transition threshold is exhibited. In addition, extending the flat shear region could increase the BAE width, resulting in stronger EP transport. Furthermore, nonlinear simulation by only considering n=1 and n=2 modes demonstrates that the low-energy EPs, as an intermediate, gain energy from n=2 mode, which subsequently transfers energy to the n=1 mode through resonant interaction.

Insights into stripping losses of negative ions in an ITER-like pre-acceleration system

Abstract The ELISE test facility at IPP Garching hosts an RF-driven negative hydrogen ion source and extraction and acceleration system. Its target is to demonstrate the performance foreseen for the ITER neutral beam injection (NBI) system in terms of extracted current density (329 A m−2 in hydrogen, 286 A m−2 in deuterium), electron-ion-ratio ( < 1) and pulse length (up to 3600 s in deuterium and 1000 s in hydrogen). NBI systems are compromised by a process commonly known as stripping losses (neutralization of negative ions before they achieve full acceleration). According to theoretical estimations, for a source filling pressure of p fill = 0.3 Pa, 29% of the extracted H − / D − ions are lost by stripping in the ITER full-scale NBI system. Experimentally, stripping losses are monitored using Beam Emission Spectroscopy (BES). Previous experimental measurements of the stripping losses at ELISE yielded values around 1.7%, which were much lower than the 10% predicted for the pre-accelerator system. The notable difference has sparked concern about the conventional interpretation of the BES experimental measurements used at IPP. The Bavarian Beam Code for Negative Ions (BBCNI) is a full 3D particle tracking code that can also produce synthetic BES spectra. BBCNI is used to evaluate how accurately different analysis techniques determine the stripping losses from the BES. This is achieved by comparing the results with the total simulated count of stripping losses. The analysis method that produces the most accurate results is identified and then systematically applied to evaluate ELISE’s data from various experimental campaigns. For a nominal source filling pressure p fill = 0.3 Pa an average of 5.8% is measured experimentally when evaluating the data with this method. Although higher than previously determined with BES, stripping losses are still smaller than predicted values. This may open the option to increase the filling pressure in the source as a means to facilitate achieving the targeted ITER conditions.

Fast ion studies in the extended high-performance high βP plasma on EAST

Abstract Comprehending and optimizing fast ion behaviors is critical for the enhancement of performance in Experimental Advanced Superconducting Tokamak (EAST). This study explores the potential benefits of several factors that can improve the fast ion confinement. First, experiments show the change in the direction of the NBI2 from counter-I p to co-I p leads to a significant reduction in fast ion losses. TRANSP/NUBEAM simulation and tomography results based on fast-ion D-alpha measurements reveal that after the neutral beam injection (NBI) upgrade, the beam ion prompt loss is reduced by approximately 50%. Second, the upgraded ion cyclotron resonant frequency (ICRF) antenna at the N-port features twice the coupling resistance of the original antennas at EAST. This improved ICRF power coupling has enhanced the synergistic heating effect of NBI + ICRF, where the ICRF wave field accelerates beam ions at the harmonics. Experiments demonstrate that NBI + ICRF synergistic not only enhances plasma neutron yield and β P, but also accelerates beam ions to hundreds of keV. Further, the electron density and the neutral beam voltage have been optimized to reduce the fast ion slowing-down time and beam ion losses. Experimental and simulation results indicate that increasing the electron density reduces beam ion losses and enhances the bootstrap current fraction. While higher beam voltage results in a slight decrease in beam power absorption, it can increase the fraction of bootstrap current. With the understanding of these optimization of fast ion confinement, experiments have demonstrated fully non-inductive operation at high density (n e/n G ∼ 0.67, β P ∼ 3.1, β N ∼ 2.1, H 98,y2 ∼ 1.2) even without the support of co-I p beam NBI2. This investigation presents a potential regime to enhance fast ion confinement and extend performance in the high β P plasma for future experiments.

Suppression of core temperature fluctuations by edge cooling in the J-TEXT tokamak

Abstract The suppression of core temperature fluctuations due to edge cooling in the J-TEXT tokamak is presented. The supersonic molecular beam is injected into the low density plasmas and the core temperature rise appears. The staggered time correlation technique is utilized to infer the temperature fluctuations from an electron cyclotron emission radiometer (ECE). The existing correlation ECE (CECE) also enables the observation of the temperature fluctuations simultaneously. A significant flattening of the density gradients appears almost in the whole plasmas after the cold pulse injection. The behaviors of the temperature fluctuations from both ECE and CECE show a good agreement, except for the fluctuation level, which exhibits a relative variation of approximately 10% − 50%. The relative intensity of temperature fluctuations decreases within the surface of r / a ∼ 0.8 due to the edge cooling. The cross-power analysis and the agreement in measurements suggest that temperature fluctuations from turbulence inferred from a single ECE channel may be possible. Linear simulations suggest the drop in temperature fluctuation intensity may relate to the trapped electron mode turbulence stabilization. This paper also demonstrates the evolution of both gradients and fluctuations before and after supersonic molecular beam injection with density scans.

Separation of Plasma Species for Investigating the Impact of Hydrogen Plasmas on the Work Function of Caesiated Surfaces

In negative hydrogen ion sources in situ adsorption of Cs is typically used to generate low work function converter surfaces. The achievement of a temporally stable low work function coating is, however, challenging due to the hydrogen plasma interaction with the surface. Particularly in ion sources for neutral beam injection systems for fusion with pulse durations of minutes to hours temporal instabilities are a major issue and limit the source performance. To clarify the influence of the hydrogen plasma on the converter surface, investigations are performed at an experiment equipped with an absolute work function diagnostic based on the photoelectric effect. Caesiated surfaces are exposed to the full plasma impact by the generation of plasmas in front of the surface as well as to selected plasma species (H atoms, positive ions and VUV/UV photons) from an external plasma source to identify driving mechanisms that lead to surface changes. Depending on the exposure time and initial surface condition, the plasma strongly affects the surface in terms of work function and quantum efficiency (QE). For degraded Cs layers (work function ≥3 eV) a favorable increase in QE and reduction in work function can be achieved, while for Cs layers with an ultra-low work function of 1.2-1.3 eV the opposite is true. It is found that each plasma species can influence the Cs layers and that VUV photons lead to a work function increase of ultra-low work function layers. For sufficiently high VUV fluences a severe work function increase by 0.5 eV is given, highlighting the relevance of photochemical processes in the plasma-surface interaction and demonstrating that ultra-low work function layers are not stable in a hydrogen plasma environment.

Charge-exchange measurements of high-energy fast ions in LHD using negative-ion neutral beam injection

A new sightline geometry for the fast-ion D-alpha (FIDA) diagnostic on the Large Helical Device (LHD) has been confirmed to measure signals for high-energy fast ions produced by negative-ion neutral beam injection. The newly installed sightline uses a 180 keV tangential negative-ion neutral beamline as the active source. Due to the small angle between the beamline and FIDA sightline, the relative velocity between fast ions and injected neutrals is small. This allows for high-energy fast ions just below the beam injection energy to produce measurable Doppler-shifted FIDA emission. Experiments were conducted at LHD in order to compare the new sightline, which views a high-energy negative-ion tangential beamline, and the old sightline, which views a low-energy perpendicular positive-ion neutral beamline. The measured FIDA signal is validated against predictions from the synthetic fast-ion diagnostic code FIDASIM with a distribution function modelled by the 5D transport code GNET. The results of the experiment confirm that reducing the viewing angle with a tangential active beam allows FIDA diagnostic to view high-energy fast ions with a sufficient signal-to-noise ratio.

Status and perspective of ICARUS-T600 detector at the Fermilab Short-Baseline Neutrino program

The ICARUS collaboration has employed the 760-ton T600 detector in a successful three-year physics run at the underground LNGS laboratory, performing a search for anomalous νe appearance in the CERN Neutrino to Gran Sasso beam, which contributed to the constraints on the allowed neutrino oscillation parameters to a narrow region around 1 eV. After a significant overhaul at CERN, the T600 detector has been installed at Fermilab. In 2020 the cryogenic commissioning began with detector cool down, liquid argon filling and recirculation. ICARUS started its operation collecting the first neutrino events from the Booster Neutrino Beam and the Neutrinos at the Main Injector beam off-axis, which were used to test the ICARUS event selection, reconstruction and analysis algorithms. ICARUS successfully completed its commissioning phase in June 2022, moving then to data taking for neutrino oscillation physics. In the short term, ICARUS will be able to either confirm or refute the claim by Neutrino-4 short-baseline reactor. At the completion of the Short-Baseline Near Detector, near and far detectors will join within the Fermilab Short-Baseline program searching for evidence of sterile neutrinos. measurements of neutrino cross sections with the NuMI beam and several Beyond-Standard-Model searches. In this presentation, the technical achievements of the ICARUS detector subsystems (Time Projection Chambers, Light Photo-detection System, Cosmic Ray Tagger, Trigger and Data Acquisition) during the commissioning phase and early data taking will be presented; the prospects for the first physics analysis will be reported.

Investigation on the density shoulder near the separatrix through monostatic reflectometry in EAST tokamak

Abstract The density shoulder represents a universal physical phenomenon that is closely related to the particle and energy transports occurring within the scrape-off layer (SOL) region of tokamak devices. A novel method has been developed to identify the density shoulder through the analysis of the bump structure in the time delay spectra from monostatic microwave reflectometry in EAST tokamak, obviating the need for density profile reconstruction. The density shoulder in EAST is characterized by a number of distinctive features. The density shoulder is mostly situated at a distance of 0–3 cm from the last closed flux surface, with a width of a few centimeters. No significant correlation is observed between its occurrence and the auxiliary heating or the confinement state. In the case of H-mode with quasi-coherent mode (QCM), a significant and positive correlation is observed between the density shoulder amplitude and QCM intensity. In the case of grassy-edge localized mode (ELM)-like H-mode, a density shoulder is also observed during the inter-ELM stage. Furthermore, as supersonic molecular beam injection (SMBI) deposits occur within the range of ρ = 0.9 ∼ 1, the density shoulder is also enhanced during the SMBI fueling process. Moreover, it appears that the neutral pressure has a more pronounced impact on the overall offset of the density profile than the strength of the density shoulder. These results collectively indicate that the outward particle transport from the pedestal to the SOL region plays a crucial role in the evolution of the density shoulder.

Neural networks for reconstruction and uncertainty quantification of fast-ion phase-space distributions using FILD and INPA measurements

Abstract This study introduces the use of a deep convolutional neural network for reconstructing fast-ion velocity distributions from fast-ion loss detectors and imaging neutral particle analyzers (INPAs), automatically integrating uncertainty quantification through Monte Carlo dropout. The network-based reconstructions reveal pitch-angle splitting in high-energy features of lost fast-ion velocity distributions at ASDEX Upgrade during active neutral beam injection, a previously observed phenomenon now confirmed through neural networks. Moreover, contrary to common theories attributing these high-energy features to edge localized mode (ELM)-driven acceleration, we provide experimental evidence that they also occur in type-I ELM-quiescent phases. Additionally, we demonstrate improved reconstructions from INPA measurements, both synthetic and from an ASDEX Upgrade commissioning discharge, with the reconstructions closely matching TRANSP simulations. These findings suggest that neural networks can provide robust reconstructions with well-defined uncertainties, improving the reliability of interpretations of fast-ion behavior in magnetically confined plasmas.

Divertor Tokamak Test: Impact of NBI shine-through and beam-plasma interaction on Divertor Tokamak Test facility

IntroductionIn this work, we aim to explore numerically the behavior of beam energetic particles in the Divertor Tokamak Test (DTT), a superconductive device equipped with a Neutral Beam Injection (NBI) system capable of injecting neutrals up to 510 keV.MethodWe explore beam ionization and beam slowing down for different DTT plasma scenarios. Numerical simulations are performed using the ASCOT suite of codes, including a wide-range scan of plasma density and beam injection energy. For different plasma conditions, we estimate shine-through losses, including the heat fluxes on the first wall thanks to dedicated particle tracing simulations. Orbits of newly-born fast ions are characterized by means of the constant of motion phase space, showing how trapped energetic particles’ population and prompt losses change with plasma density and NBI energy.Results and discussionSlowing down simulations show that NBI injection at 510 keV is well coupled to DTT plasmas. DTT NBI will be one of the sources of auxiliary ion heating, with an absorbed power ratio of up to ∼50% depending on plasma and beam parameters. At low plasma densities, energetic particle confinement is less efficient, and NBI power and/or energy reduction is expected.

Analysis of High-Voltage Holding Capability for CRAFT NNBI Negative Ion Source with 400 kV

CRAFT (Comprehensive Research Facility for Fusion Technology) is a large scientific device that is preferentially deployed for the construction of major national science and technology infrastructures. A negative ion–based neutral beam injection system with a beam energy of 400 keV, a beam power of 2 MW, and a beam duration of 100 s, it was designed to deliver an energetic neutral beam for fusion research. Among the crucial components of this system, the high-power negative ion source stands out, and the voltage holding capability of its accelerator with double-stage is a commonly encountered issue. To address this concern, a comprehensive investigation has been conducted that focused on the gaps between the acceleration grids and grid supports in terms of voltage holding capability utilizing empirical formulas. The results of this investigation revealed that an acceleration gap of 81 mm and a grid support gap of 65 mm can be achieved through the implementation of empirical formulas, which aligns with the requirement of 200 kV for each stage. In addition, the preliminary experimental results showed that the voltage holding capability of the adjacent grids can reach up to 200 kV when the gap between the adjacent grids was designed to be 90 mm. These findings provide a foundation for the subsequent design of a high-power ion source characterized by both high energy and a large area.

Kinetic instabilities in two-isotopic plasma in the gas-dynamic trap magnetic mirror

A fusion neutron source (FNS) based on the gas-dynamic trap (GDT, Budker Institute, Novosibirsk) is considered for confinement of two-species plasma heated by neutral beam injection in a regime where the fast ion distribution function is far from Maxwellian. Kinetic instabilities are expected to develop in this regime, and in this paper we investigate the ion-cyclotron instability evolving in moderate densities of pure hydrogen and mixed deuterium–hydrogen target plasmas. The properties of the studied unstable mode, such as its azimuthal wavenumbers, propagation direction and its being affected by changes in the bulk plasma density and composition, allow us to identify it as the drift cyclotron loss cone (DCLC) instability. This mode scatters fast ions and thereby leads to drops in diamagnetic flux signals and increases longitudinal energy and particle losses, with the average energy of the lost ions estimated to be far above the temperature of warm Maxwellian ions. Our interpretation is that the unstable wave grows due to interaction with the fast ions located near the loss cone in the velocity space and scatters them. Applying the method of suppressing the DCLC instability by filling the loss cone with warm plasma, we have determined the values of plasma density and deuterium percentage that allow us to suppress the DCLC instability in the GDT. These findings justify using mixed bulk plasmas in fusion neutron source operation.

Studies of beam ion confinement to enhance plasma performance on EAST

A key physics issue for achieving steady-state high-performance plasmas on EAST tokamak is to decrease beam-ion losses to improve plasma confinement during neutral beam injections (NBIs). To decrease the beam losses, previous counter-I p NBI injections are upgraded to co-I p injections. Analysis shows that due to the reversed direction of drift across the flux surfaces caused by the pitch angle, the beam prompt loss fraction decreases from about 49% to 3% after the upgrade. Moreover, because of the change of entire beam path, beam shine-through (ST) loss fraction for counter-I p tangential and counter-I p perpendicular injections is reversed to co-I p tangential and co-I p perpendicular injections, respectively. Due to the change in the initial trapped-confined beam ion fraction caused by the peaked pitch profiles, the losses induced by toroidal ripple field are also reversed after the upgrade. To further improve the beam-ion confinement under the present NBI layout, the amplitudes of toroidal field are increased from 1.75 to 2.20 T. Result shows that, due to the smaller orbit width and peaked pitch angle profile, the beam prompt loss power is lower with higher toroidal field. Due to the synergy of higher initial trapped-confined beam ion fraction and narrower Goldston-White-Boozer (GWB) boundary, the loss induced by ripple diffusion is higher with higher toroidal field. The combined effect of beam ST loss, prompt loss and ripple loss, contributes to the increase in beam ion density. The decrease in beam loss power enhances beam heating efficiency, especially the fraction of beam heating ions. Finally, comparison between simulation and measurement by 235U fission chamber (FC) indicates that the increase in neutron rate is mainly contributed by improvement of beam-ion confinement. This study can provide potential support for beam operation and high-T i experiment on EAST tokamak.