Threshold Power Research Articles

Investigating the effect of termination capacitor on E–H mode transition in radio frequency inductively coupled plasma

In this work, the effects of stringing termination capacitors on the external circuit parameters, plasma parameters, and mode transition in radio frequency (RF) inductively coupled Ar discharges are investigated. It has been demonstrated that at low pressure (1 Pa), in the absence of termination capacitors, the plasma parameters and external circuit parameters exhibit a continuous variation with increasing RF power. The plasma density is observed to decrease with decreasing capacitance value in the E mode when the termination capacitor is inserted, while the plasma density is increased with decreasing capacitance value in the H mode. During the E–H mode transition process, both the plasma parameters and the external circuit parameters undergo a discontinuous change characterized by a distinct “jump” in each parameter. By increasing and then decreasing RF power, the evolution of each parameter creates a significant hysteresis. As the termination capacitance decreases, the power threshold of the H–E mode transition decreases, resulting in a larger hysteresis loop. The termination capacitor, which is connected in series at the end of the coil, can alter the voltage distribution on the RF antenna. This alteration results in a reduction in the potential difference between the coil and the “common ground,” which effectively diminishes the electrostatic field. Furthermore, the electron energy probability function indicates that the addition of the termination capacitor results in a reduction in the proportion of energetic electrons in the E mode, accompanied by a reduction in the plasma potential.

Material-dependent TMI and SBS threshold power simulations of Yb-doped fiber amplifiers

The influence of engineered glass compositions for the enhancement of the TMI and SBS threshold powers in kW class Yb-doped fiber amplifiers is explored with validated simulations. A reduction in the thermo-optic coefficient and an increase in the thermal conductivity raises the TMI threshold power while the SBS threshold power is increased by a reduction in the Brillouin gain. A quasi-analytic model is extended to include the local bend loss of thermally loaded coiled gain fibers and is validated with well-documented experimental results. The range of material coefficients is determined by recent material investigations. It is found that a 55% reduction in the thermo-optic coefficient results in a 75% increase in the TMI threshold power and a 43% increase in the thermal conductivity results in a 30% increase in the threshold power. A 75% reduction in the Brillouin gain is found to increase the SBS threshold by 200%. Simulated threshold powers are in qualitative agreement with recent experimental results. These simulations provide a quantitative measure of the threshold power improvements that can be achieved with engineered glass compositions.

Effects of blood flow restriction on internal and external training load metrics during acute and chronic short-term repeated-sprint training in team-sport athletes

ABSTRACT This study examined internal, external training loads, internal:external ratios, and aerobic adaptations for acute and short-term chronic repeated-sprint training (RST) with blood flow restriction (BFR). Using randomised crossover (Experiment A) and between-subject (Experiment B) designs, 15 and 24 semi-professional Australian footballers completed two and nine RST sessions, respectively. Sessions comprised three sets of 5–7 × 5-second sprints and 25 seconds recovery, with continuous BFR (45% arterial occlusion pressure) or without (Non-BFR). Banister’s, Edwards’, Lucia’s training impulse, and session rating of perceived exertion training load (sRPETL) were calculated. External training loads were determined by total work done (TWD). Ventilatory threshold power outputs were assessed during a graded exercise test post-RST. Internal training loads were comparable between conditions, though BFR reduced (p < 0.02) TWD during acute (−4.9%) and short-term chronic (−10.0%) RST compared to Non-BFR. Furthermore, BFR increased (p = 0.049) the sRPETL:TWD ratio during short-term chronic (+14.8%), but not acute RST. First and second ventilatory threshold power outputs improved (+8.3% and + 4.2%, respectively) similarly for both groups following RST. Repeated exposure to progressively overloaded RST with BFR increases internal demands for a given workload, which may promote beneficial physiological adaptations compared to Non-BFR, though aerobic performance was not further enhanced.

Optimizing microstructure and minimizing defects in laser-arc hybrid additive manufacturing of Al-Cu alloy: the role of laser mode

Recently, laser-arc hybrid additive manufacturing (LAHAM) has emerged as a transformative method for producing lightweight aluminum alloys, valued for its advantageous surface quality and mechanical properties. In this study, the effect of various laser modes on macro morphology, defect formation, microstructure evolution, and mechanical properties of Al-Cu alloy were investigated. At a laser power threshold of 1.5 kW, the transition from conduction mode to keyhole mode was observed. When the keyhole formed, the molten metal exhibited enhanced fluidity, resulting in smoother surfaces and more uniform spreading. As laser power increased, although hydrogen-induced pores (HIP) were notably reduced, the keyhole-induced pores (KIP) began to appear. During subsequent depositions, the intense reheating effects from laser facilitated a transformation from reticular eutectics (RE) along grain boundaries to granular eutectics (GE). Additionally, recrystallization and formation of Σ3 coincidence site lattice (CSL) boundaries were restricted due to the reduced residual stress caused by moderating cooling rates, alleviating stress concentration near pores during deformation. Therefore, optimal results were achieved in conduction mode at a laser power of 1 kW, achieving highest tensile strengths of 269.5 MPa and 260.1 MPa, and elongations of 19.6% and 13.8% in horizontal and vertical directions, respectively.

Access and sustainment of ELMy H-mode operation for ITER Pre-Fusion Power Operation plasmas using JINTRAC

Abstract In the initial stages of ITER operation, ELM mitigation systems need to be commissioned. This requires controlled flat-top operation in type-I ELMy H-mode regimes. Hydrogen or helium plasma discharges are used exclusively in these stages to ensure negligible production of neutrons from fusion reactions. With the expected higher L-H power threshold of hydrogen and helium plasmas compared to corresponding D and D/T plasmas, it is uncertain whether available auxiliary power systems are sufficient to operate in stable type-I ELMy H-mode. This has been investigated using integrated core and edge/SOL/divertor modelling with JINTRAC. Assuming that the L-H power threshold is well captured by the Martin08 scaling law, the presented simulations have found that 30 MW of ECRH power is likely required for the investigated hydrogen plasma scenarios, rather than the originally planned 20 MW in the 2016 Staged Approach ITER Baseline. However, past experiments have shown that a small helium fraction (~10 %) can considerably reduce the hydrogen plasma L-H power threshold. Assuming that these results extrapolate to ITER operation regimes, the 7.5MA/2.65T hydrogen plasma scenario is likely to access stable type-I ELMy H-mode operation also at 20 MW of ECRH.

Analysis of output characteristics of LD end-pumped 2.94 μm continuous-wave Er:YAG laser

Abstract Considering self-saturation effect and thermal effect, a detailed theoretical analysis of the output characteristics of the 2.94 μm continuous-wave (CW) Er:YAG laser with a 10 mm long 50 at.% Er:YAG crystal end-pumped by a 976 nm LD is carried out by solving transient rate equations and heat conduction equations. It is shown that there is a minimum pump power threshold of 0.27 W for the 2.94 μm CW Er:YAG laser. The main factor which limits the significant increase of pump power is the thermal damage risk of the crystal’s pump end-face coating. To minimize the risk, the CW operating temperature of the pump end-face coating is set to be no higher than 200 °C, and therefore the value of the pump beam waist radius is limited to 40 μm ⩽ w 0 ⩽ 490 μm. Within the range, a maximum 2.94 μm CW laser output power of 4.03 W is achieved with a pump beam waist radius of 100 μm. By bonding a 2.5 mm long YAG crystal at the pump-end of the Er:YAG crystal, the CW operating temperature of the pump end-face coating is reduced to the room temperature of 20 °C. Under this condition, the limiting factor for a substantial increase of pump power is the thermal damage risk induced by large interior thermal stress of the Er:YAG crystal. Assuming the interior thermal stress of the CW operating Er:YAG crystal is less than 341 MPa according to the material characteristics, the pump power can be increased by increasing the pump beam waist radius. When the beam waist radius is 430 μm, a maximum 2.94 μm CW laser output power of 38.7 W is obtained. Compared with the unbonded condition, the output power level of the 2.94 μm CW Er:YAG laser is promoted.

Effects of Increasing Vocal Tract Insertion Depth in Semi-Occluded Vocal Tract Exercises on an Excised Canine Model.

Straw phonation therapy, a form of semi-occluded vocal tract (SOVT) exercise, is commonly used to help treat various voice disorders. Although straw phonation therapy has been studied extensively for decades, the impact of straw depth on vocal function remains unexplored. This study aims to quantify the effects of various straw vocal tract insertion depths (VTID) into the vocal tract on common aerodynamic parameters such as phonation threshold pressure (PTP), phonation threshold flow (PTF), and phonation threshold power (PTW) in an ex vivo canine model. It was hypothesized that increasing the VTID of the straw would reduce the PTP, PTF, and PTW. Five excised canine larynges were mounted on a pseudolung apparatus and attached to a simulated vocal tract in an acoustic sound booth. Two straw depths (20.0 and 60.0mm) were tested to determine the effect of VTID on ease of phonation as indicated by the aerodynamic parameters of PTP, PTF, and PTW. The control had no straw and a VTID of 0.0mm. The straw diameter and length above the simulated vocal tract were consistent between the straws. Sustained phonation was achieved, and aerodynamic data was collected and analyzed. Both straw treatment groups exhibited significant reductions in PTP and PTW compared to the control. However, there were no significant differences between the 20.0 or 60.0mm straw depths in PTP, PTF, or PTW. The presence of a straw significantly reduced PTP and PTW, but VTID did not appear to influence these outcomes. This supports previous straw phonation therapy research suggesting that straw phonation therapy is beneficial primarily due to the presence of the straw rather than the depth of insertion. Future studies should explore the combined effects of varying straw diameters, lengths, and depths to optimize SOVT therapy for clinical use.

Integrated optical switches based on Kerr symmetry breaking in microresonators

With the rapid development of the Internet of Things and big data, integrated optical switches are gaining prominence for applications in on-chip optical computing, optical memories, and optical communications. Here, we propose a novel approach for on-chip optical switches by utilizing the nonlinear optical Kerr effect induced spontaneous symmetry breaking (SSB), which leads to two distinct states of counterpropagating light in ring resonators. This technique is based on our first experimental observation of on-chip symmetry breaking in a high-Q (9.4×106) silicon nitride resonator with a measured SSB threshold power of approximately 3.9 mW. We further explore the influence of varying pump powers and frequency detunings on the performance of SSB-induced optical switches. Our work provides insights into the development of new types of photonic data processing devices and provides an innovative approach for the future implementation of on-chip optical memories.

Investigation of magnetic fluctuations in L-H and H-L transition dynamics on DIII-D

Abstract The dynamics of the L-H transition is not fully understood, with many parameters changing the threshold power to enter H-mode and the self-regulation between zonal flows and turbulence in the plasma edge. This paper presents power threshold analysis for DIII-&amp;#xD;D L-H and H-L transitions, as well as measurements of pedestal temperatures for these transitions. A comparison is made between an L-H transition and H-L transition of comparable Psep exhibiting oscillatory behaviour, showing symmetry between forward and backward transition dynamics. Information geometry analysis has been performed on measurements of plasma density fluctuations, perpendicular plasma velocity fluctuations, and magnetic field fluctuations to investigate the self-regulation of these variables during the transitions. Perpendicular flow evolution is shown to dominate the transition dynamics in both directions, but self-regulation behaviour is observed between all three variables. A strong correlation between magnetic fluctuation information rate and density fluctuation information rate for these two shots indicates the strong influence of magnetic behaviour on both the L-H and H-&amp;#xD;L transition, and that these transition dynamics have an electromagnetic contribution. Some parameter dependencies of the magnetic fluctuation activity are presented.

Exercise training load prediction based on improved genetic algorithm

With the advancement of digital information age, all kinds of sports also widely used digital mining technology, the technology can promote athletes’ professional level and physical quality, is in the field of sports improve athletes and coaches more effective way, but the bicycle sports for digital mining and research is still in the early state. Cyclists load ability in training is mainly influenced by the body function, the relationship between the two is complicated, this paper is the training load ability and physical function as a research object, explore the specific connection between the two aspects of cyclists, by constructing the cyclist training load prediction model, to apply in the “bicycle team training analysis system”. Strive to promote the overall development of cycling, to provide a basis for the scientific training of talents and training. The cyclist training load prediction model created in this paper can provide a scientific design basis for the training of athletes. When analyzing the body function, this paper mainly analyzes the influence of athletes on conforming sports through 25 aspects such as maximum oxygen intake, functional threshold power and blood oxygen saturation. Because the factors of athletes and the predicted results show non-linear correlation, this paper selects the BP neural network algorithm in the model algorithm, and the adaptive genetic algorithm of the selection operator is adjusted and optimized to clarify the initial weights and thresholds of BP neural network. Finally, the practice has proved that the improved algorithm has a more prominent global optimization ability, and the accuracy of the model has reached 93.28%.

Enhanced Performance of High-Power InAs/GaAs Quantum Dot Lasers Through Indium Flushing

InAs/GaAs quantum dots (QDs) appear promising for optoelectronic applications. However, the inhomogeneous broadening caused by natural strain and the non-uniform size distribution deteriorates the device performance based on multi-stacked QD layers. In this study, In-flush was incorporated during the epitaxy, and the photoluminescence (PL) linewidth was significantly narrowed to 26.1 meV for the flushed sample and maintained to 27.3 meV for the unflushed sample. The flushed sample shows better device performance in threshold current (0.229 to 0.334 A at 15 °C), power (1.142 to 1.113 W at 15 °C), and characteristic temperature (51 to 39 K in the range of 55~80 °C) compared with the unflushed sample.

Enhancing scalable reconfigurable manufacturing systems through robust optimisation: energy efficiency and cost minimisation under uncertainty

Reconfigurable manufacturing systems are dynamic systems designed with scalable and flexible production capabilities to address changing market demands. This paper presents a novel multi-objective integer programming model aimed at optimising the configuration and capacity scalability of reconfigurable machine tools in uncertain environments. The model focuses on minimising three key objectives: total energy consumption, unused capacity, and total cost. It incorporates critical manufacturing constraints such as peak power thresholds and limited tool availability. To effectively manage uncertainty, particularly in demand fluctuations, a scenario-based robust optimisation approach is applied, striking a balance between solution robustness and model adaptability. A comprehensive case study demonstrates the model's effectiveness, comparing deterministic and uncertain solutions. Additionally, sensitivity analyses are performed on parameters such as peak power thresholds, risk coefficients, and infeasibility weights, highlighting their impact on system performance. The results provide insights into the efficient design and operation of scalable reconfigurable manufacturing systems under uncertainty, with recommendations for future research directions.

Parametric decay of a gyrotron beam due to a rotating magnetic island in ASDEX Upgrade

Abstract We investigate parametric decay instabilities (PDIs) of electron cyclotron waves due to a rotating neoclassical tearing mode (NTM) in ASDEX Upgrade. Strong scattering characteristic of PDIs is observed in a discharge where a (2,1) NTM has been identified. By mapping out the structure of the NTM toroidally, it is possible to determine the phases of the NTM which enable the decay to occur. Signatures of PDIs are seen when the edges of the magnetic island intersect the gyrotron beam path, but not when the O-point of the magnetic island is located directly in front of the gyrotron launcher. We propose an explanation using a simplified model, which reproduces features of the scattering in 1D particle-in-cell (PIC) simulations. The simulations show that a density perturbation caused by an NTM can give rise to a lowered PDI power threshold. The threshold is lowest in an intermediate density perturbation region where certain waves excited in PDIs can become trapped. The PIC simulations show that several decay and combination events involving approximately half frequency waves produce waves slightly downshifted from the main pump frequency of 140 GHz. This is the first time PIC simulations based on experimental profiles reproduce signals close to the pump frequency, which result from interactions with half frequency waves. The numerical results support previous observations from the tokamak TEXTOR.

Sub-GHz optical pulsing using a thermally generated heterostructure with strong optomechanical coupling.

Thermal engineering can be used to exploit absorption in a silicon optical cavity. In this work, the steady state profile of the heat generated by absorption is shaped and used to generate a dynamic heterostructure in a weakly confined silicon optical cavity. This is demonstrated in an edge defect photonic crystal optomechanical cavity to produce phonon lasing and sub-GHz optical pulsing with photon-phonon cooperativity of 0.088. It is typically challenging to meet the conditions for phonon lasing. The cooperativity must be at least unity, and the cavity operated in the optomechanical sideband resolved regime. Here, our thermal design uses absorption-generated heat to modify the refractive index of the cavity and dynamically form a heterostructure, compressing the optical mode volume and relaxing the constraints on the optical quality factor, mechanical quality factor, and threshold power. The compressed mode then couples to a thermo-optical/free-carrier-dispersion limit cycle, resonantly exciting the optomechanical cavity. While edge defects have been shown to have high optomechanical sensitivity, the cavity lacks sufficient mode confinement to generate the limit cycle without the thermal heterostructure. The formation of the heterostructure results in phonon lasing and sharp optical pulsing at 30 MHz. These results demonstrate the novel use of thermal engineering to initiate phonon lasing with further improvements leading to a fully integrated, sub-GHz optical frequency comb.

Continuous‐wave and cavity‐dumped 1064 nm Nd:YVO4 laser based on the magneto‐optical effect

AbstractIn this paper, continuous‐wave and cavity‐dumped Nd:YVO4 lasers are studied. Firstly, through theoretical analysis and numerical simulation, the output characteristics of a continuous‐wave laser based on the magneto‐optical effect are analysed using the rate equation. The continuous adjustment of output power and pump threshold power is realised using the magneto‐optical effect to rotate the polarisation direction of laser. The theoretical simulation results show that the output power of the laser could be effectively controlled under different magnetic field intensities. On this basis, the authors explore the cavity‐dumped laser system based on the magneto‐optical effect. By adjusting the intensity of the magnetic field and rising edge time, the pulse width and waveform could be flexibly adjusted. The relationship between the magnetic field intensity in the low Q period and the spot radius of the pump and the signal beam and the output energy and the output pulse waveform is analysed. These research results lay a foundation for further optimising the design and application of magneto‐optical effect lasers.

Cycling Isokinetic Peak Force Explains Maximal Aerobic Power and Physiological Thresholds but Not Cycling Economy in Trained Triathletes.

Background: Assessments of muscle strength help prescribe and monitor training loads in cyclists (e.g., triathletes). Some methods include repetition maximum, joint isokinetic tests, and indirect estimates. However, their specificity for cycling's dynamic force application and competitive cadences is lacking. This study aims to determine the influence of the cycling isokinetic peak force (cIPF) at different cadences on aerobic performance-related variables in trained triathletes. Methods: Eleven trained male athletes (33 ± 9.8 years, 173.1 ± 5.0 cm height, 73.9 ± 6.8 kg body mass, and ≥5 years of triathlon experience) were recruited. Maximal oxygen consumption (VO2 max), ventilatory thresholds (i.e., VT1 and VT2), and cIPF were assessed. cIPF testing involved 10 s sprints at varied cadences with 4 min rest intervals. Pedaling cadences were set at low (60 rpm), moderate (80 and 100 rpm), and high (120 and 140 rpm) cadences. A regression model approach identified cIPF related to aerobic performance. Results: IPF at 80 and 120 rpm explained 49% of the variability in power output at VT1, 55% of the variability in power output at VT2, 65% of the variability in power output at maximal aerobic power (MAP), and 39% of the variability in VO2 max. The cycling economy was not explained by cIPF. Conclusions: This study highlights the significance of cIPF, particularly at moderate to high cadences, as a determinant of aerobic-related variables in trained triathletes. Cycling cIPF should be tested to understand an athlete's profile during crank cycling, informing better practice for training specificity and ultimately supporting athletes in achieving optimal performance outcomes in competitive cycling events.

Mapping and Optically Writing Nanogap Inhomogeneities in 1-D Extended Plasmonic Nanowire-on-Mirror Cavities.

Tightly confined plasmons in metal nanogaps are highly sensitive to surface inhomogeneities and defects due to the nanoscale optical confinement, but tracking and monitoring their location is hard. Here, we probe a 1-D extended nanocavity using a plasmonic silver nanowire (AgNW) on mirror geometry. Morphological changes inside the nanocavity are induced locally using optical excitation and probed locally through simultaneous measurements of surface enhanced Raman scattering (SERS) and dark-field spectroscopy. The increasing molecular SERS intensity and corresponding redshift of cavity plasmon modes by up to 60 nm indicate atomic-scale changes inside the nanocavity. We correlate this to diffusion of silver atoms into the nanogap, which reduces the nanogap size and enhances the optical near-field, enhancing the SERS. These induced changes can be locally excited at specific locations along the length of the nanowire and remain stable and nonreversible. Polymer surface coating on the AgNW affects the power threshold for inducing atom migration and shows that strong polyvinylpyrrolidone (PVP)- Ag binding gives rise to higher power thresholds. Such extended nanogap cavities are an ideal system to provide robust SERS while withstanding high laser powers. These results provide insights into the inhomogeneities of NW nanocavities and pave the way toward spatially controlled NW lithography in ambient conditions.

Mid‐Infrared on‐Chip Soliton Self‐frequency Shift in Chalcogenide Glass Waveguide

AbstractMid‐infrared soliton lasers leveraging the Raman self‐pumping induced soliton self‐frequency shift (SSFS) effect offer continuously tunable, highly efficient, femtosecond coherent sources that are essential for applications such as spectroscopy, metrology, and quantum optics. However, despite significant advancements in fluoride and chalcogenide fiber platforms, realizing mid‐infrared Raman soliton lasers on on‐chip platforms remains challenging. In this study, the first experimental demonstration of a mid‐infrared Raman soliton laser in an on‐chip Ge28Sb12Se60 (GeSbSe) chalcogenide glass waveguide is presented. A fully fiberized femtosecond fiber laser, centered at 1.96 µm and emitting 246 fs pulses at a 50 MHz repetition rate, is utilized as the pump source, establishing a fiber‐to‐chip configuration. The waveguides are meticulously fabricated using e‐beam lithography and plasma etching, achieving high optical quality and precision in the mid‐infrared regime. Through precise geometrical dispersion engineering, a Raman soliton laser is achieved that continuously tunes from 1960 to 2145 nm within a 32.5 mm long snakelike GeSbSe strip waveguide. The threshold for pump peak power is remarkably low, at just 14.1 W (3.47 pJ). Additionally, a more than one‐octave‐spanning near to mid‐infrared supercontinuum (1320–2760 nm at 22.9 pJ), reinforced by the combined Kerr and Raman effects, is also realized, confirming the versatile performance of the proposed GeSbSe waveguide. These findings pave the way for mid‐infrared on‐chip Raman soliton lasers, highlighting their potential for power‐efficient, low‐cost, and field‐deployable on‐chip applications in the mid‐infrared regime.

Key factors influencing cycling performance and overall race time in the Ironman 70.3 for amateur athletes

Abstract Purpose Previous study has shown that cycling is the most predictive modality in the Ironman 70.3 triathlon distance. As a result, understanding the physiological and anthropometric variables that are mostly closely related to cycling performance can help coaches and athletes to direct their training programs. This study aimed to investigate the physiological, anthropometric, and general training characteristics influencing overall race time and cycling split time in Ironman 70.3. The present study also investigated the significance of body composition as a performance-related variable. Methods A questionnaire was used to assess training characteristics in 12 athletes (six men and six women), body composition in dual X-ray absorptiometry, and physiological variables in an incremental cardiopulmonary test. Ironman 70.3 São Paulo–Brazil 2023 was completed by all participants. The relationship between performance and the variables measured were investigated, and a multiple regression model for cycling split time and overall race time was developed. Results Functional threshold power (FTP) can predict cycling split time in Ironman 70.3 (r2 = 0.638, p = 0.002). Maximal oxygen uptake ($$\dot{\text{V}}$$ V ˙ O2max) (r2 = 0.667, p = 0.001) can predict overall race time. FTP and $$\dot{\text{V}}$$ V ˙ O2max are also strongly related to lean mass and fat mass percentage. Conclusion While FTP is the most important predictor of cycling split time, $$\dot{\text{V}}$$ V ˙ O2max is the most important predictor of overall race time in an Ironman 70.3. Furthermore, because body composition (fat mass %) and muscle mass (kg) are variables strongly related to FTP and $$\dot{\text{V}}$$ V ˙ O2max, we recommend that coaches and athletes consider to conduct a body composition assessment.

Non-linear dependence of ion heat flux on plasma density at the L–H transition of JET NBI-heated deuterium–tritium plasmas

Abstract Recent JET D–T campaigns opened the possibility of unique isotope studies to investigate the L–H transition physics in view of reactor plasmas and to study the origin of the observed power threshold minimum. In the present paper, we characterise L–H transitions in the low and high-density branches of JET NBI-heated D–T plasmas. As discussed in the paper, L–H transition has been hypothesised to be determined by the transport power losses of plasma ions, i.e. the so-called ion heat flux (Q i). We present the first power balance analysis of JET NBI-heated D–T plasmas to evaluate the ion heat flux at the transition. Due to the experimental setting being similar to previous JET D experiments, we also directly compare the results, discussing the isotope effect and similarities between datasets. First, we find an isotope effect between D and D–T Q i, with a lower Q i in D–T plasmas. We confirm that the ion heat flux deviates from density linearity compared to the linear trend observed in wave-heated D plasmas of other tokamaks. The deviation we observe in NBI-heated L–H transitions happens at an isotope-dependent density. Plasma edge rotation correlates with Q i deviation from density linearity in the low-density branch. However, further investigations would be required to assess the role of rotation on Q i and the power threshold minimum at JET. At low plasma density, NBI power dominates Q i, while increasing the density makes the equipartition power dominant. We finally compare our results with hypotheses proposed from evidence in other tokamaks to present a complete overview of ion heat flux analyses in D and D–T NBI-heated plasmas at JET.