Effects of composition and structure on hydrogen incorporation in tungsten oxide films deposited by sputtering

The effects of composition and structure on hydrogen incorporation in tungsten oxide films were investigated. Films were deposited on carbon and SiO₂ substrates using a reactive sputtering by varying the substrate temperature from 30 to 600 °C in argon and oxygen mixture. The films were characterized using X-ray diffraction (XRD), Rutherford backscattering spectroscopy (RBS), elastic recoil detection analysis (ERDA) and Raman scattering. XRD patterns showed amorphous structure in the films deposited below 400 °C and (0 1 0) oriented monoclinic WO₃ in the films deposited beyond 400 °C. The results of RBS and ERDA indicated that hydrogen concentration in the amorphous films increased from 0.1 to 0.7 H/W with changing the composition from WO_0.25 to WO₃. The hydrogen concentration in WO₃ films decreased to 0.4 H/W with increasing the substrate temperature during deposition. The Raman spectra of the WO₃ films revealed that decreasing of W⁶⁺O terminals was related to decreasing of the hydrogen concentration. It was considered that the incorporated hydrogen in tungsten oxide films was bonded at the end of W⁶⁺O terminals.     

C-selective infrared multiple photon dissociation of β-propiolactone by a free electron laser

The irradiation of a free electron laser at Tokyo University of Science (FEL-TUS) to β-propiolactone molecules in the gas phase has efficiently induced the infrared multiple photon dissociation of the compound in the wavenumber regions of 1000-1100 and 1700-2000 cm⁻¹. The products were carbon dioxide and ethylene at equal amounts, where carbon dioxide was enriched with ¹³C under selected irradiation conditions. The relative yields of products and the selectivity of ¹³C were examined under various experimental conditions; the maximum ¹³C atom fraction of 59% was achieved when 2.5 Torr β-propiolactone was irradiated by FEL pulses at 1750 cm⁻¹ with a fluence of 5.8 J cm⁻². One of the reasons of this high selectivity is a large isotope shift of ∼47 cm⁻¹ for the CO stretching vibration around 1880 cm⁻¹, which is larger than the energy resolution of FEL-TUS. Another possible factor may be a shorter micropulse interval (∼350 ps) of FEL-TUS than the collisional frequency of β-propiolactone molecules in the gas phase, which prevents the collisional energy transfer from ¹³C molecules to ¹²C molecules during successive micropulses.     

Structural characterizations and the third-order nonlinear optical properties of poly(2,5-didecyloxy)phenylene films modified by N ions implantation

Poly(2,5-didecyloxy)phenylene (PDDOP) films implanted by 30 keV nitrogen ions (N⁺) with the dose rang of 10¹⁵-10¹⁷ ions/cm² were characterized by FTIR-ATR spectra, UV-VIS spectra and X-ray photoelectron spectroscopy, which showed that the C-H bonds of the PDDOP films were largely broken and new bonds like CC, CN and CN were formed as the increasing ion fluence. The third-order nonlinear optical susceptibilities (χ⁽³⁾) were measured by degenerate four-wave mixing (DFWM) technique at 532 nm. The results demonstrated that the (χ⁽³⁾) value of PDDOP films was maximized to 4.19 × 10⁻¹¹ esu at an ion dose of 1.15 × 10¹⁷ ions/cm², which was 4.4 times larger than that of the pristine film. The enhanced third-order nonlinear properties may attribute to the enlarged expansion coefficient and the enhanced absorption coefficient of the bombarded films at proper N⁺ ions dose.     

Ageing of EUROBITUM bituminised radioactive waste: An ATR-FTIR spectroscopy study

The extent of the physico-chemical processes of concern in the study of the acceptability of Eurobitum bituminised radioactive waste for underground disposal (water uptake by hygroscopic NaNO₃ - swelling - pressure build-up - NaNO₃ leaching) will depend on the degree of ageing of the bituminous matrix. In the work reported here, the ageing behaviour was studied by comparing the characteristics of 25 years old radioactive Eurobitum with those of 25 years old non-radioactive Eurobitum samples that were heated or gamma-irradiated in the presence or absence of oxygen. Chemical changes in the bitumen structure were followed in the mid-infrared region with Attenuated Total Reflectance Fourier Transform InfraRed Spectroscopy (ATR-FTIR) by measuring the evolution of the band heights at 1700 cm⁻¹ (CO functional groups) and 1600 cm⁻¹ (CC double bonds). Needle penetration depths and ring and ball softening points were determined for some samples. Oxidation of bitumen in the presence of oxygen results in a distinct increase of both the number of CO and CC functionalities, with a positive linear relationship existing between the two groups. The production of CO functional groups seems to promote the generation of CC double bonds. Heating at 130 °C is much more efficient than gamma irradiation at low to moderate dose rates (20-140 Gy/h) to oxidise the bitumen. As the oxygen concentration decreases, for instance by diffusion limitation deeper inside the bitumen, the number of CO and CC functionalities formed per unit of time decreases. A similar behaviour was observed for 25 years old radioactive Eurobitum. In absence of oxygen, gamma irradiation still results in a small increase of the number of CO functional groups, probably by oxygen still adsorbed on the bitumen, and in a relatively higher amount of CC double bonds. The surface layer (<5 cm) of 25 years old radioactive Eurobitum was heavily oxidised. The material had become very hard and brittle, and was full of small fissures. Due to these fissures, radio-oxidation processes took also place deeper inside the waste. The consequences of these observations for the long-term behaviour of Eurobitum in underground disposal conditions are discussed.     

Deuterium retention in plasma spray tungsten coatings exposed to low-energy, high flux D plasma

Two types of porous plasma spray tungsten coatings deposited onto stainless steel and graphite substrates were exposed to low-energy (76 eV ), high-flux (10²² D/m² s) D plasma to ion fluences of (3-4) × 10²⁶ D/m² at various temperatures. Deuterium retention in the W coatings was examined by thermal desorption spectroscopy and the D(³He,p)⁴He nuclear reaction, allowing determination of the D concentration at depths up to 7 μm. The relatively high D concentration (above 0.1 at.%) at depths of several micrometers observed after D plasma exposure at 340-560 K can be related to accumulation of D₂ molecules in pores, while at temperatures above 600 K deuterium is accumulated mainly in the form of D atoms chemisorbed on the inner pore surfaces. At exposure temperatures above 500 K, the D retention in the plasma spray W coating on graphite substrate increases significantly due to trapping of diffusing D atoms at carbon dangling bonds located at the edge of a graphite crystallite.     

Effect of gamma irradiation on a polymer electrolyte: Variation in crystallinity, viscosity and ion-conductivity with dose

PEO(1 − x)NH₄ClO₄(x) samples with x = 0.18 are irradiated with gamma doses varying up to 50 kGy. DSC and XRD studies indicate, in general, a decrease in crystallinity with dose. Measurement of viscosity of aqueous solutions of the irradiated samples at the same concentration, shows that there is overall chain scission on irradiation, though there is evidence of some cross-linking also at higher doses. This is corroborated by FTIR measurements. The ion-conductivity shows a strong increase for irradiation dose 35 kGy. This suggests that there is a possibility of improving polymer electrolyte properties on gamma irradiation.     

Degradation of elastomer by heat and/or radiation

This article studied various problems on the degradation of elastomers by heat and/or radiation. Three kinds of elastomers were irradiated and evaluated by the radiation resistant property using the measurement of tensile test. The fluorine containing elastomer, which has excellent heat resistant properties, was found to be less durable for irradiation than ethylene-propylene-diene (EPDM) elastomer. Ten kinds of different compounding formulas of EPDM were prepared to investigate whether the compounding for heat resistant has durability for irradiation. The thermal exposure was performed in an air oven. The duration of thermal exposure at 140 °C was 384 h. The irradiation condition was 5.0 kGy/h at 70 °C, and the total dose was 0.9 MGy. Elongation retained was taken for the evaluation of the stability. It was found that the formulas for improving the thermal stability did not bring radiation resistant of samples in the experiment.The rate constant of the increase in CO concentration by heat and radiation was measured and defined as k_c(h) and k_c(r), respectively. The rate constant of that under the combined addition of the heat and the radiation is expressed as k_c(h + r). Eq. (1) was obtained by the experiment and it was found that there is a synergistic relationship between heat and radiation on the increase in CO concentration

(1)     

Ga NMR and magnetic susceptibility in δ-phase of Pu1−xGax (x = 0.05, x = 0.08) alloys

⁶⁹Ga nuclear magnetic resonance spectra, line shifts (⁶⁹K) and nuclear spin-lattice relaxation rate have been measured in the 20 years aged Pu_0.95Ga_0.05 and in fresh prepared Pu_0.92Ga_0.08 alloys, stabilized δ-phase, at magnetic field of 9.4 T in the temperature range (10-500) K. The line shift and are determined correspondingly by the static and fluctuating-in-time parts of the local magnetic field that originates in transferred hyperfine coupling the Ga nuclear spin with the nearest f-electron environment of more magnetic Pu.Temperature behavior of the resonance properties is found the same in fresh Pu_0.92Ga_0.08 and aged Pu_0.95Ga_0.05 alloy. The NMR results are in favor that δ-phase of Pu_1−xGa_x alloys represents at T > 200 K the Kondo lattice, in which the localized electronic spins fluctuate independently from each other without any macroscopic coherence. The coherent state like in heavy-fermion liquids emerges in Pu_0.95Ga_0.05 below T^∗ = 200 K. A little bit higher estimate of crossover temperature T^∗ = 250 K was founded for Pu_0.92Ga_0.08.     

Structural characterization of Fe/Ag bilayers by RBS and AFM

Fe/Ag thin films are intensively investigated due to their special magnetic properties. Recently a deposition-order dependent asymmetric interface has been found. When iron is grown on silver, the interface is sharp, while the growth of Ag on Fe results in a long, low-energy tail of the Ag peak in the Rutherford backscattering spectrometry (RBS) spectra. The main purpose of this paper is to show that the low-energy Ag tail is caused by grain boundary diffusion, and that, when elevating the growing temperature of the Ag layer this effect becomes more significant. Two sets of polycrystalline and epitaxial Fe/Ag bilayers were prepared simultaneously onto Si(1 1 1) and MgO(1 0 0), respectively. The iron layers were grown at 250 °C and annealed at 450 °C in both sets, while the Ag layer was grown in the first set at room temperature (RT) and in the second set at 250 °C (HT). The sample composition, the interface sharpness and the quality of the epitaxy were studied by Rutherford backscattering spectrometry (RBS) combined with channeling effect. The surface morphology was determined by atomic force microscopy (AFM). RBS spectra show that in the case of RT samples the epitaxial MgO/Fe/Ag bilayer has sharp, well-defined interface, while for the polycrystalline Si/Fe/Ag sample the silver peak has a low-energy tail. Both the Fe and Ag peaks smeared out in the case of HT samples. AFM-images show that the RT samples have a continuous Ag layer, while the HT samples have fragmented surfaces. The RBS spectra taken on the HT samples were successfully simulated by the RBS-MAST code taking into account their fragmented structures.     

A microscopic and Synchrotron-based characterization of urban particulate matter (PM10-PM2.5 and PM2.5) from Athens atmosphere, Greece

Urban particulate matter (PM₁₀-PM_2.5 and PM_2.5) from Athens (Greece) atmosphere, primarily investigated by SEM-EDS, was further studied in the FLUO and SUL-X beamlines of ANKA Synchrotron facility (KIT, Germany). The SR μ-XRF study showed both geological (e.g. CaTi, CaK and CaSrKRb) and anthropogenic particles exhibiting heavy metal combinations such as FeCo, FeCoCuV and ZnV. It was also revealed that very hazardous metalloids and heavy metals, namely As and Pb, are concentrated in isolated respirable (PM_2.5) microparticles. It was attempted to investigate the oxidation state of As by means of μ-XANES. The As K-edge XANES spectrum of the sample shows a main peak at about 11.874 keV which matches adequately with the As(V) reference spectrum but part of the As seems to have a lower oxidation state (most probably As(III)). This is the first non-bulk study with regard to the partitioning and solid-state speciation of hazardous chemical elements in urban atmospheric microparticles from greater Athens area, rated as an alpha-world city with a population of ca. 4 million people.     

Structural modification in amorphous silica after exposure to low fluence 355 nm laser irradiation

UV laser irradiation induced structural modification in amorphous silica was characterized using Fourier transform infrared and X-ray induced photoelectron spectroscopy. Laser irradiation experiment was conducted using a 3ω, 355 nm beam from a pulsed Nd-YAG laser with pulse length of 6.8 ns and laser repetition rate of 1 Hz at ambient conditions. The examined laser fluence was controlled at a relatively low level, ranging from 0 to 4 J/cm². The IR spectra revealed that the vibration frequency of the rocking mode of SiOSi covalent bond shifted to lower wave number, while the bending mode and asymmetric stretching mode of SiOSi covalent bond shifted to higher frequency. This result suggested that the length of SiOSi covalent bond was decreased, the bond angle was increased and the irradiation modified material was densified after irradiation. The high resolution XPS spectra of Si 2p and O 1s illustrated the chemical shift of silicon and oxygen ions after irradiation. The XPS chemical shift of the Si 2p peak about 1.1 eV revealed the existence of low valence silicon ions Si³⁺ species in silica glass after irradiation. The chemical shift of the O 1s peak about 0.9 eV illustrated the emergence of non-bridging oxygen ions during laser irradiation. The deconvoluted peak area and FWHM value of low valence silicon ions and non-bridging oxygen ions all exhibited exponentially growth as the linearly elevation of laser fluence. UV laser-induced photolysis of SiO covalent bond was suggested to be responsible for the formation and increase of low valence silicon ions and non-bridging oxygen ions. These FT-IR and XPS data revealed that short range structural modifications were important structure alterations in silica glass before the emergence of distinct and large size damage crater.     

Investigations on the structural and optical properties of the swift heavy ion irradiated 6HSiC

Single crystal 6HSiC wafers have been irradiated with 150 MeV Ag¹²⁺ ions with fluences ranging from 1 × 10¹¹ to 1 × 10¹³ ions/cm² at 300 K. The defect accumulation as a function of fluence was studied to determine changes in structural and optical properties. The variation in the fundamental Raman modes of the crystalline 6HSiC due to irradiation has been correlated with the disorder accumulation. The creation of defect states due to irradiation in the bandgap affects the blue-green photoluminescence emission in the irradiated samples. The UV-Visible absorption studies support the existence of defect states in the bandgap which is observed by the shift in the absorption edge towards the lower energy side with increasing fluence. Time Correlated Single Photon Counting photoluminescence decay results suggest that the existing defect states are radiative, exhibiting three lifetimes when irradiated with a fluence 5 × 10¹¹ ions/cm². The total number of lifetime components was reduced for a fluence 1 × 10¹³ ions/cm² as the defect states produced increase the non-radiative defect centres. These results suggest that the accumulation of defects due to irradiation at fluences 5 × 10¹¹ and 1 × 10¹³ ions/cm² are degenerate configurations which exhibit multiple lifetimes in photoluminescence studies. It is inferred that the optically active defect states influence the transition rate of charge carriers in this device material.     

The effect of vacancy created by ion irradiation on the ordering of FePt: A first-principle study

Ion irradiation has been used to promote ordering processes and to modify the magnetic properties of magnetic thin films. The major reason for ion irradiation reducing the ordering temperature is the introduction of a number of vacancies. The vacancy and its influence on the ordering temperature and magnetic properties in L1₀ ordered FePt are investigated by first-principle simulation. The vacancy formation energy for Fe and Pt in FePt alloy are 1.45 and 2.25 eV respectively. The calculated order-disorder transition temperature of Fe₅₀Pt₅₀ is 1680 K. The order-disorder transition temperatures for Fe vacancy and Pt vacancy models are about 50 K and 200 K lower than that of the stoichiometric Fe₅₀Pt₅₀ alloy respectively. The results suggested that the vacancy in FePt alloy favors the ordering process. The saturation magnetization of stoichiometric L1₀ FePt is 1070 emu/cc and these of Fe and Pt vacancy are 1027 and 1075 emu/cc, respectively.     

On the impact of reactive solutes on radiation induced oxidative dissolution of UO2

The impact of 2-propanol (100 mM), NaCl (0.1 - 2 M) and Fe(II)(aq) (10 μM) on the radiation induced oxidative dissolution of UO₂ is investigated experimentally by γ-irradiating a UO₂ pellet immersed in aqueous solution containing 10 mM together with one of the studied solutes and measure the U(VI) concentration in solution as a function of irradiation time. The solution was saturated with one of the following gases; Air, N₂O, inert gas (N₂ or Ar) in order to vary the experimental conditions and/or avoid the influence of oxygen. The results show that, in the presence of oxygen, 2 M chloride decrease the rate of UO₂ dissolution whereas the dissolution rate increases somewhat in the presence of 100 mM 2-propanol. Under oxygen-free conditions both 2 M chloride, 100 mM 2-propanol and 10 μM Fe(II)(aq) decrease the rate of UO₂ dissolution. The trends in dissolution rates were reproduced by calculations based on previously determined rate constants for UO₂ oxidation and oxidant concentrations obtained from numerical simulation of radiolysis in the corresponding homogeneous systems (taking reactions between the different solutes and the products of water radiolysis as well as changes in oxygen solubility into account). However, the results indicate that we cannot fully account for the G-values in 2 M chloride solution or all reactions involving Cl⁻ in the aqueous phase. This calls for further studies of the chloride system.     

Structural and gasochromic properties of epitaxial WO3 films prepared by pulsed laser deposition

The structural and gasochromic properties of epitaxial tungsten trioxide (WO₃) thin films, prepared by ArF excimer pulsed laser deposition under the controlled oxygen atmosphere, have been investigated. The WO₃ films were grown on the α-Al₂O₃ substrates, as the oxygen pressure ranged from 0.57 to 1.20 Pa and the substrate temperature ranged from 432 to 538 °C. The deposited films were characterized by Rutherford backscattering spectroscopy (RBS)/channeling, X-ray diffraction, X-ray pole figures and Raman spectroscopy. RBS and XRD results demonstrated that monoclinic WO₃ (0 0 1) films were successfully grown on the α-Al₂O₃ substrates. The crystal quality was improved by increasing both the oxygen pressure and the substrate temperature. Gasochromic coloration in the WO₃ films by exposure to diluted hydrogen gas was found to correlate with the crystal quality of the films. The gasochromic coloration was suppressed by the epitaxial growth of the films.     

Proton irradiation effect on microstructure, strain localization and iodine-induced stress corrosion cracking in Zircaloy-4

The radiation-induced microstructure, strain localization, and iodine-induced stress corrosion cracking (I-SCC) behaviour of recrystallized Zircaloy-4 proton-irradiated to 2 dpa at 305 °C was examined. <a> type dislocation loops having 1/3〈1 1  0〉 Burgers vector and a mean diameter and density of, respectively, 10 nm and 17 × 10²¹ m⁻³ were observed while no Zr(Fe,Cr)₂ precipitates amorphization or Fe redistribution were detected after irradiation. After transverse tensile testing to 0.5% macroscopic plastic strain at room temperature, almost exclusively basal channels were imaged. Statistical Schmid factor analysis shows that irradiation leads to a change in slip system activation from prismatic to basal due to a higher increase of critical resolved shear stresses for prismatic slip systems than for basal slip system. Finite element calculations suggest that dislocation channeling occurs in the irradiated proton layer at an equivalent stress close to 70% of the yield stress of the irradiated material, i.e. while the irradiated layer is still in the elastic regime for a 0.5% applied macroscopic plastic strain. Comparative constant elongation rate tensile tests performed at a strain rate of 10⁻⁵ s⁻¹ in iodized methanol solutions at room temperature on specimens both unirradiated and proton-irradiated to 2 dpa demonstrated a detrimental effect of irradiation on I-SCC.     

X-ray absorption studies of chlorine valence and local environments in borosilicate waste glasses

Chlorine (Cl) is a constituent of certain types of nuclear wastes and its presence can affect the physical and chemical properties of silicate melts and glasses developed for the immobilization of such wastes. Cl K-edge X-ray absorption spectra (XAS) were collected and analyzed to characterize the unknown Cl environments in borosilicate waste glass formulations, ranging in Cl-content from 0.23 to 0.94 wt.%. Both X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) data for the glasses show trends dependent on calcium (Ca) content. Near-edge data for the Ca-rich glasses are most similar to the Cl XANES of CaCl₂, where Cl⁻ is coordinated to three Ca atoms, while the XANES for the Ca-poor glasses are more similar to the mineral davyne, where Cl is most commonly coordinated to two Ca in one site, as well as Cl and oxygen nearest-neighbors in other sites. With increasing Ca content in the glass, Cl XANES for the glasses approach that for CaCl₂, indicating more Ca nearest-neighbors around Cl. Reliable structural information obtained from the EXAFS data for the glasses is limited, however, to ClCl, ClO, and ClNa distances; ClCa contributions could not be fit to the glass data, due to the narrow k-space range available for analysis. Structural models that best fit the glass EXAFS data include ClCl, ClO, and ClNa correlations, where ClO and ClNa distances decrease by approximately 0.16 Å as glass Ca content increases. XAS for the glasses indicates Cl⁻ is found in multiple sites where most Cl-sites have Ca neighbors, with oxygen, and possibly, Na second-nearest neighbors. EXAFS analyses suggest that ClCl environments may also exist in the glasses in minor amounts. These results are generally consistent with earlier findings for silicate glasses, where Cl⁻ was associated with Ca²⁺ and Na⁺ in network modifier sites.     

Photoluminescence study of swift heavy ion (SHI) induced defect centers in sapphire

Single crystals of sapphire (Al₂O₃: Fe, Ti, Cr) were irradiated at room temperature with different fluence of 100 MeV Ni ions. Photoluminescence (PL) spectra of pristine and irradiated sapphires were recorded at room temperature under 2.8 eV blue excitation. A broad emission band consists of two bands centered at 516 nm corresponding to F₂ defect center and 546 nm corresponding to defect center was observed. The intensity of these defect centers was found to vary with the fluence. defect center develops at low fluence reaching maximum at 5 × 10¹⁶ ions/m² and finally decreasing at higher fluence. The behavior is interpreted in terms of creation of defect centers, their clustering and annihilation.     

Irradiation effect of carbon negative-ion implantation on polytetrafluoroethylene for controlling cell-adhesion property

We have investigated the irradiation effect of negative-ion implantation on the changes of physical surface property of polytetrafluoroethylene (PTFE) for controlling the adhesion property of stem cells. Carbon negative ions were implanted into PTFE sheets at fluences of 1 × 10¹⁴-1 × 10¹⁶ ions/cm² and energies of 5-20 keV. Wettability and atomic bonding state including the ion-induced functional groups on the modified surfaces were investigated by water contact angle measurement and XPS analysis, respectively. An initial value of water contact angles on PTFE decreased from 104° to 88° with an increase in ion influence to 1 × 10¹⁶ ions/cm², corresponding to the peak shifting of XPS C1s spectra from 292.5 eV to 285 eV with long tail on the left peak-side. The change of peak position was due to decrease of C-F₂ bonds and increase of C-C bonds with the formation of hydrophilic oxygen functional groups of OH and CO bonds after the ion implantation. After culturing rat mesenchymal stem cells (MSC) for 4 days, the cell-adhesion properties on the C⁻-patterned PTFE were observed by fluorescent microscopy with staining the cell nuclei and their actin filament (F-actin). The clear adhesion patterning of MSCs on the PTFE was obtained at energies of 5-10 keV and a fluence of 1 × 10¹⁵ ions/cm². While the sparse patterns and the uncontrollable patterns were found at a low fluence of 3 × 10¹⁴ ions/cm² and a high fluence of 3 × 10¹⁵ ions/cm², respectively. As a result, we could improve the surface wettability of PTFE to control the cell-adhesion property by carbon negative-ion implantation.     

Design and experimental results of feedback control of Ohmic-heating transformer magnetic flux by LHCD power in HT-7 Tokamak

In order to make a research on long pulse or even steady state operation with non-inductive drive in plasma discharge, a new feedback control scheme instead of the previous one has been designed and operated in HT-7 [HT-7 team presented by J. Li, et al., Plasma Phys. Control. Fusion 42 (2) (2000) 135-146] Tokamak experiment, 2004. Consumption of iron-core transformer magnetic flux (MFT) is feedback controlled for the first time by power of lower hybrid current drive (LHCD) P_LH, when the Ohmic-heating circuit current can maintain the plasma current I_P constant with another feedback control loop, which make MFT evolve at alternating-change state to avoid flux saturation. Plasma current I_P can be maintained steadily up to 120 s in this operation mode at reduced plasma parameters (I_P ≈ 50-100 KA, average density , P_LH = 100-200 KW). Design and experimental results are presented in the paper, which including control model analysis, configurations of control system and MFT feedback control experiments in HT-7. The high voltage power supply (HVPS) of LHCD is the main controller that regulates the LHCD power into the plasma to control the MFT.