Robust Plasma Conditions Research Articles

Factors affecting phosphonate measurement by inductively coupled plasma optical emission spectroscopy (ICP-OES) in oilfield produced waters

ABSTRACT Phosphonate scale inhibitors are commonly used to mitigate scaling problems in oilfields. Continuous measurement of phosphonate in the produced waters in the levels of few mgL−1 using ICP-OES is usually conducted to monitor and assess phosphonate treatments, and to qualify the discharged produced waters. These measurements of phosphonates in high salt producedwaters suffer from severe matrix effects, contamination, samples preservation and dilution issues. The results in this study showed that conducting measurements when the sample total dissolved solids (TDS) was higher than the calibration standards TDS that leads to lower phosphonate results, while higher results obtained when the sample TDS was lower than the calibration standards TDS. The matrix elements Na, Mg, and Ca were found to depress the emission lines intensity of phosphorus and their effect was in the order of: Ca > Na > Mg for the lines 213.617 nm, 253.561 nm, and in the order of Mg > Ca> Na for the line 214.914 nm. Besides, it was found that diluting the samples of low phosphonate content leads to lower phosphonate results; therefore, phosphonate measurements are better be conducted on undiluted samples. The instrument robust operating conditions at low nebulizer and pump uptake rates, high RF power and with the use of baffled cyclonic spray chamber showed better sensitivity, LOD and LOQ compared to the plasma non-robust conditions. The use of internal standard and quality control QC program along with the instrument setup at robust plasma conditions allowed direct measurement of phosphonate down to 1 mgL−1 without dilution, desalination, preconcentration or matrix matching. It was also found that Ca and Fe affect phosphonate measurements due to the high phosphonate precipitation/adsorption potential on their compounds, and acid preservation methods using HCl were found to be the best method to avoid phosphonate precipitation or adsorption.

Determination of key elements in plant samples by inductively coupled plasma optical emission spectrometry with electrothermal vaporization

Inductively coupled plasma optical emission spectrometry combined with electrothermal vaporization (ETV) was used for determination of Ba, Ca, Co, Cu, Fe, K, Mg, Mn, P, Sr, Zn, S, and Se in plant materials. Optimized temperature program comprised a pyrolysis phase (duration 60 s and max. temperature 600 °C) and analytical phase (duration 70 s and temperature gradually increasing to 2500 °C); dichlorodifluoromethane (known as Freon R12) was used as a chemical modifier. High plasma power for robust plasma conditions was used. Calibrations based on certified reference materials of plant and animal origin and aqueous calibration solutions were linear for most of the used spectral lines and were stable for several months. Limits of detection were in the range from 7 to 1100 mg/kg for plant main elements and from 0.074 to 4.3 mg/kg for plant minor and trace elements. The precision of results was below 6%, and recovery was 83–116%. Results of inductively coupled plasma optical emission spectrometry with ETV were in good agreement with results of inductively coupled plasma optical emission spectrometry with pneumatic nebulization sample introducing system and inductively coupled plasma mass spectrometry obtained in the same laboratory, and differences between results were generally lower than 10%. Then, the amounts of selected elements, which are important indicators of plant health and nutritional value, were determined. The agreement of our results with results obtained in another laboratory was acceptable in case of S, K, Ca, and Se (differences lower than 10%). In case of determination of Mg, P, Cu, Mn, and Zn, the differences ranged from 20 to 25%.

Application of flexible multi-elemental ICP-OES detection in fractionation of potentially toxic element content of solid environmental samples by a sequential extraction procedure

Remediation of areas contaminated by potentially toxic elements (PTE) requires the appropriate assessment of the environmental mobility of contaminants. The fractionation techniques developed for agrochemical and environmental purposes model the pathways of environmental mobilization mainly by sequential extraction procedures. In Europe mostly the simplified extraction scheme proposed by Community Bureau of Reference (BCR) in 1993 is widely used, why only to this certified sediment sample (BCR 701) is available, certified for fractionation of six elements (Cu, Cd, Cr, Ni, Pb, Zn). In the BCR extracts the reagent- solvents applied in leaching steps cause strong matrix interferences when for determination the PTE-contents of these solutions the multielemental capacity of inductively coupled plasma optical emission spectrometry (ICP-OES) should be utilized. Due to the different source of contamination the flexible multi-elemental ICP-OES method should be applied for analysis of the different BCR-extractant-solvent media which makes possible the reliable detection of all occurring PTE in the area. For this purpose as the most adequate solution the application of ICP-OES spectrometer with charge-coupled device (CCD)-detection was selected which is able to record the entire spectral range between 120 and 800 nm. On the basis of detailed study of BCR-solvent-matrix- and expected-analite-line interferences it was established that the sensitivities of the prominent lines of pollutant elements strongly depend on the type of extractants. For improving the accuracy of analytical results obtained for soils and environmental sediments, matrix matched calibration, internal standardization and robust plasma conditions were recommended and optimized. The successful application of this methodology is presented for a PTE-contaminated lake sediment sample and for selected typical Hungarian soil samples stored in sample bank of Hungarian Soil Protection Information and Monitoring System.

A Pragmatic Approach to Coping with Matrix Effects during ICP-MS Analysis of Trace Elements in Silicate Rocks and Calibration of REE Interferences

Operating an Agilent 7700X ICP-MS spectrometer under robust plasma conditions (1550 W) with a He-filled octopole collision cell and analysing solutions (−1 total dissolved solids) still suffered analyte peak suppression due to matrix effects. International reference rocks BCR-1, BHVO-1, AGV-1, G-2 and BCR-2 all showed count rate reductions for 36 elements (mass range 7Li to 238U) averaging ~10% but with no dependence on isotope mass. Use of an internal standard (103Rh) and/or using a ten-fold dilution of sample solutions reduced these effects but problems with reduced count rates combined with larger errors for some elements introduced other problems. The best approach was to normalise the count rates for each element in the other samples against those for BCR-1 as an external standard; thus the count suppression due to the matrix effect is corrected for each individual element. This approach provides standardization “traceability” in line with the ERM ISO/IEC requirement. Experiments are also reported on quantifying the proportions of Ba and selected REE oxide/hydroxide components versus parent isotopes (XO/X and XOH/X). This information is essential for correcting peak interferences on higher mass number REE for the rock samples, and equations are developed to use measured CeO/Ce and CeOH/Ce ratios to predict such values for any other member of the REE suite. Concentrations obtained show excellent agreement with recommended values for the international reference materials especially for the REE. Robust data are also provided for two other standard rocks: nepheline syenite STM-1 and quartz syenite CAAS-1; the latter shows exceptional enrichments of Zr, REE, Th, and U.

Optimization of simultaneous determination of metals in commercial pumpkin seed oils using inductively coupled atomic emission spectrometry

In this work, the inductively coupled plasma atomic emission spectrometry (ICP-AES) was developed and validated for determination of 27 metals in nine pumpkin oils from two production processes (cold pressed and roasted). A microwave assisted digestion was applied for the dissolution of the samples. To evaluate plasma robustness and analytical performance, the Mg II 280.270 nm/Mg I 285.213 nm (Mg II/Mg I) line intensity ratio was used. The robust plasma conditions in axial/radial view mode were reached at an RW power of 1150 W and an argon nebulizer flow rate of 0.5 L/min. The method is evaluated by application of the standard addition method and by recovery test. In general, the recoveries for all elements in pumpkin seed oils were between 90% and 110% except, only for Cd, Pb and As they were <90% and >110%. The most abundant element is K followed by, Mg, P, Ca and Na. Pumpkin seed oils were also found to be a good source of Fe, Zn, Cu and Mn. The highest levels of analyzed elements were found in pumpkin seed oils producing from the roasted pumpkin seed paste. In all samples, the content of heavy metals was below the recommended tolerable levels proposed by Joint FAO/WHO Expert Committee on Food Additives and does not a pose a health risk for the consumer. The levels of the metals in pumpkin seed oils were also compared with those reported by the literature. Cluster analysis (CA) of the analytical data confirmed the observed differences between oils from two production processes.

Accuracy of laser-ablation (LA)-MC-ICPMS Sr isotope analysis of (bio)apatite – a problem reassessed

Accurate in situ Sr isotope analysis of (bio)apatite via ‘robust-plasma’ laser-ablation MC-ICPMS with negligible 40Ca31P16O and reliable 87Rb interference correction.

Investigation of a measure of robustness in inductively coupled plasma mass spectrometry

In industrial/commercial settings where operators often have minimal expertise in inductively coupled plasma (ICP) mass spectrometry (MS), there is a prevalent need for a response factor indicating robust plasma conditions, which is analogous to the Mg II/Mg I ratio in ICP optical emission spectrometry (OES), whereby a Mg II/Mg I ratio of 10 constitutes robust conditions. While minimizing the oxide ratio usually corresponds to robust conditions, there is no specific target value that is widely accepted as indicating robust conditions. Furthermore, tuning for low oxide ratios does not necessarily guarantee minimal matrix effects, as they really address polyatomic interferences. From experiments, conducted in parallel for both MS and OES, there were some element pairs of similar mass and very different ionization potential that were exploited for such a purpose, the rationale being that, if these elements were ionized to the same extent, then that could be indicative of a robust plasma. The Be II/Li I intensity ratio was directly related to the Mg II/Mg I ratio in OES. Moreover, the 9Be+/7Li+ ratio was inversely related to the CeO+/Ce+ and LaO+/La+ oxide ratios in MS. The effects of different matrices (i.e. 0.01–0.1M Na) were also investigated and compared to a conventional argon plasma optimized for maximum sensitivity. The suppression effect of these matrices was significantly reduced, if not eliminated in the case of 0.01M Na, when the 9Be+/7Li+ ratio was around 0.30 on the Varian 820 MS instrument. Moreover, a very similar ratio (0.28) increased robustness to the same extent on a completely different ICP-MS instrument (PerkinElmer NEXION). Much greater robustness was achieved using a mixed-gas plasma with nitrogen in the outer gas and either nitrogen or hydrogen as a sheathing gas, as the 9Be+/7Li+ ratio was then around 1.70. To the best of our knowledge, this is the first report on using a simple analyte intensity ratio, 9Be+/7Li+, to gauge plasma robustness.

Internal standardization in axially viewed inductively coupled plasma optical emission spectrometry (ICP OES) combined with pneumatic nebulization and aerosol desolvation

Internal standardization using axially viewed inductively coupled plasma optical emission spectrometry (ICP OES) combined with pneumatic nebulization/aerosol desolvation was evaluated in the present study. The sample and internal standard (IS) solutions were mixed on-line. Spectral lines of In, Y, Ga and Ar were evaluated for internal standardization under robust plasma conditions to overcome matrix effects on Ba, Cd, Co, Cr, Zn, Pb, Sr, Mn, Cu, Ni and V quantification in digests of plant materials. In(II)230.606 nm was only effective for Cd and Pb whereas Y(II)371.029 nm or Ga(I)417.206 nm or Ga(I)294.364 nm were effective for the other investigated elements. Argon was not effective, suggesting that matrix effects were related to aerosol generation and its transport to the ICP. By using internal standardization accurate results were obtained for certified reference samples of plant materials and the relative standard deviation (RSD) was lower than 1% even for solutions with high acid concentration. The limits of quantification (LOQ) of Cr(I)357.869, Cr(II)267.716, Cu(I)327.393, Cu(II)224.700, Cd(I)228.802, Cd(II)214.440, Pb(I)217.000, Pb(II)220.353, Zn(I)213.857, Zn(II)206.200, Sr(II)407.771, Ba(II)233.527, V(II)292.464, Mn(II)257.610, Ni(II)232.003 and Co(II)228.616 nm were 0.070, 0.041, 0.065, 0.094, 0.033, 0.056, 1.33, 0.45, 0.065, 0.10, 0.005, 0.20, 0.12, 0.015, 0.10 and 0.047 μg g−1, respectively. It was concluded that the method is feasible for routine applications.

Determination of metal impurities in advanced lead zirconate titanate ceramics by axial view mode inductively coupled plasma optical emission spectrometry

An inductively coupled plasma optical emission spectrometry quantification method for the determination of Al, Ca, Cr Cu, Fe, Mn, Mg, Ni, Zn, Ba, K, In and Co in lead zirconate-titanate (PZT) ceramics, modified with strontium and chromium, was developed. Total digestion of ceramics was achieved with a HNO3, H2O2 and HF (ac) mixture by using a microwave furnace. The sensitivity of the net signal intensity respect to radiofrequency power (P) and nebulizer argon flow (FN) variations was strongly dependent of the total excitation energy of line (TEE). For lines with TEE near metastable atoms and ions of argon, an increment of the sensitivities to P and FN variation was observed. At robust plasma conditions the matrix effect was reduced for all matrices and analytes considered. The precision of analysis ranged from 3 to 13%, whereas the analytes recoveries in the spiked samples varied, mostly, from 90 to 110%. The detection limits of studied elements were from 0.004 to 10mgkg−1.

Analysis of Elemental Impurities in Photovoltaic Silicon by Inductively Coupled Plasma Mass Spectrometry

A new, simple sample preparation method which results in minimal contamination has been developed for the ultratrace interference-free analysis of solar grade silicon wafers by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Using Dynamic Reaction Cell (DRC) technology with patented dynamic bandpass tuning (DBT) and robust hot plasma conditions, the determination of many critical elements, including boron and phosphorus, without impact from interfering species is shown. For method validation, the mean results of a PV silicon wafer sample (purity > 6N) prepared with this new methodology and analyzed by ICP-MS were cross-checked with the data obtained from Glow Discharge Mass Spectrometry (GDMS). The comparative data of these two different technologies highlights the advantage of the ELAN DRC II ICP-MS for the fast determination of impurities in the PV silicon, over GDMS - which was found to be not as cost effective or time efficient.

Isotope ratio determination by laser ablation-single collector-inductively coupled plasma-mass spectrometry. General capabilities and possibilities for improvement

In this paper, the general capabilities of laser ablation-single-collector-inductively coupled plasma-mass spectrometry (LA-SC-ICP-MS) for isotope ratio determination are discussed. Some new approaches for improving the quality of the results have been investigated, and the results are presented here and compared with previously published data. In this way, an attempt is made to promote the use of this accessible technique in those contexts for which it is fit-for-purpose. Starting from a general exposition of the main factors affecting the combined uncertainty for isotopic analysis when using this technique, some general hints for method development are given and some methodological approaches permitting the results to be improved presented. In this regard, proper selection of the type of mass spectrometer, of the ICP-MS acquisition parameters, and of the detection mode used (i.e. pulse counting or analog mode) are first discussed. Secondly, different methodological approaches for stabilizing the LA-ICP-MS signal and/or filtering out large particles that would not be properly digested in the plasma are presented and critically compared in terms of precision improvement and the effect they exert on the observed mass discrimination. The use of Ne in a collision/reaction cell leads to precision improvement due to the so-called collisional damping effect, but, at a cost of strongly matrix-dependent mass discrimination. The insertion of a dual-pass spray chamber in-between the LA system and the ICP torch with simultaneous admixture of (i) a nebulized aerosol or (ii) a flow of N2 leads to improved precision while providing more robust plasma conditions, reducing the matrix-dependence of the mass discrimination effect. After evaluation of the results presented, some general hints for achieving optimal isotopic data by means of LA-SC-ICP-MS are summarized in the conclusions section. These recommended conditions provide considerable improvements with respect to the typical precision values reported for this technique (e.g., ∼0.1% RSD external precision for glass samples), such that valuable information can be obtained in many application fields.

Influence of the operating parameters and of the sample introduction system on time correlation of line intensities using an axially viewed CCD-based ICP-AES system

The influence of the acquisition and operating parameters on time correlation between emission line intensities was investigated using axially viewed inductively coupled plasma-multichannel-based emission spectrometry and various sample introduction systems. It was found that to obtain flicker-noise limited signals, necessary to compensate for time-correlated signal fluctuations by internal standardization, the flicker-noise magnitude of the sample introduction system, the integration time and the emission line intensity had to be considered. The highest correlation between lines was observed for ultrasonic nebulization with desolvatation, the noisiest system among those considered, for which the contribution of the uncorrelated shot-noise was negligible. In contrast, for sample introduction systems characterized by lower flicker-noise levels, shot-noise led to high, non-correlated RSD values, making the internal standard method to be much less efficient. To minimize shot-noise, time correlation was improved by increasing the emission line intensities and the integration time. Improvement in repeatability did not depend only on time correlation, but also on the ratio between the relative standard deviations of the analytical and reference lines. The best signal compensation was obtained when RSD values of the reference and analytical lines were similar, which is usually obtained when the system is flicker-noise limited, while departure from similarity can lead to a degradation of repeatability when using the internal standard method. Moreover, the use of so-called robust plasma conditions, i.e. a high power (1500 W) along with a low carrier gas flow rate (0.8 L/min) improved also the compensation. Finally, high correlation and consequent improvement in repeatability by internal standardization was observed also in the presence of complex matrices (sediment and soil samples), although a matrix-induced degradation of the correlation between lines was generally observed when using ultrasonic nebulization.

The determination of trace element concentrations in fly ash samples using ultrasound-assisted digestion followed with inductively coupled plasma optical emission spectrometry

A method of ultrasound-assisted digestion followed by inductively coupled plasma optical emission spectrometry (ICP-OES) used for the determination of trace element (chromium, copper, lead, nickel, vanadium and zinc) concentrations in fly ash samples was developed. All the measurements were performed in robust plasma conditions. Ultrasound-assisted digestion procedures using digestion solutions of aqua regia and hydrofluoric acid (HF) resulted in recovery rates of over 80% for all the analyte elements. Ultrasound-assisted two-step digestion with digestion solutions of 6 mL of HNO 3 (Step 1) and 3 mL of HNO 3 + 3 mL of HF (Step 2) resulted in recovery rates of over 92% for all the analyte elements with one exception, chromium, which had a recovery of about 85%. The analysis of SRM 1633b showed that the two-step ultrasound-assisted digestion method developed resulted in chromium, copper, nickel and zinc concentrations higher than the microwave digestion method standardized by the United States Environmental Protection Agency (USEPA method 3052). This is the very first time when a digestion method using ultrasound resulted in higher efficiency than microwave (USEPA method 3052) for chromium and nickel in very hard to dissolve samples. The major advantages of the ultrasound-assisted digestion over microwave digestion is the high treatment rate (about 30 samples simultaneously with a sonication time of 18 min) and the possibility to use new sample vessels without a significant increase in costs.

Determination of mineral and trace element concentrations in pine needles by ICP-OES: evaluation of different sample pre-treatment methods

In the present study, the determination of mineral and trace elements (Al, B, Ca, Cu, Fe, K, Mg, Mn, Na, P and Zn) from pine needles using three sample pre-treatment methods followed by inductively coupled plasma optical emission spectrometry, was examined. Sample pre-treatment methods tested were microwave digestion, ultrasound-assisted digestion and dry ashing. The new ultrasound-assisted digestion method was optimised by the analysis of the standard reference material (SRM) 1575a (pine needles) sample. The speed of dry ashing method was significantly increased by ultrasound dissolution after ashing. All the ICP-OES measurements were performed in robust plasma conditions which were tested by measuring the Mg II 280.270 nm/Mg I 285.213 nm line intensity ratios. The microwave digestion resulted generally in slightly higher element concentrations than ultrasound-assisted digestion. B, Cu and Na resulted in such low concentrations that they could not be accurately determined by using the microwave digestion method. The t-tests found no significant differences between the certified and the determined element concentrations of the SRM 1575a using the dry ashing method followed with ultrasound dissolution.

An ultrasound-assisted digestion method for the determination of toxic element concentrations in ash samples by inductively coupled plasma optical emission spectrometry

A method of ultrasound-assisted digestion followed by inductively coupled plasma optical emission spectrometry (ICP-OES) used for the determination of toxic element concentrations (arsenic, barium, cobalt, copper, lead, nickel, strontium, vanadium and zinc) in ash samples was developed. All the measurements were performed in robust plasma conditions which were tested by measuring the Mg(II) 280.270 nm/Mg(I) 285.213 nm line intensity ratios. The highest line intensity ratios were observed when a nebulizer gas flow of 0.6 L min −1, auxiliary gas flow of 0.2 L min −1 and plasma power of 1400 W were used for radially viewed plasma. The analysis of SRM 1633b showed that the ultrasound-assisted method developed is highly comparable with the microwave digestion method standardized by the United States Environmental Protection Agency (EPA-3052). The ultrasound-assisted digestion with a digestion solution of aqua regia and hydrofluoric acid (HF) resulted in recovery rates of over 81%. One exception is arsenic which resulted in recoveries of about 60% only; however, it could be digested with good recovery (>90%) using a digestion solution of 5 mL of water and 5 mL of aqua regia. The major advantage of the ultrasound-assisted digestion over microwave digestion is the high treatment rate (30 samples simultaneously with a sonication time of 18 min).

Real and composite emission lines as internal standards in the determination of As, Se and Sb by inductively coupled plasma optical emission spectrometry

A method that enlarges the pool of potential internal standards for axially viewed inductively coupled plasma optical emission spectrometry has been developed and evaluated. This method is based upon the visualization of the similarity of matrix-induced behavior among emission lines by principal component analysis according to the procedure suggested by Grotti et al. (J. Anal. At. Spectrom., 2003, 18, 274). For a certain analytical line, more choices of internal standards are provided from composite spectral lines created by combining real spectral lines in such a way as to integrate their characteristic behaviors. The method was applied in the determination of As, Sb and Se in solutions that modelled plant and food sample digests, to compensate for the matrix effect due to the presence of nitric or hydrochloric acids as well as a variety of matrix elements including aluminium, calcium, iron, magnesium, manganese, phosphorus, potassium, sodium, sulfur, and zinc. Under robust plasma conditions, the matrix-induced errors, which averaged between 8 and 23%, were decreased to an average of between 2 and 5% by the composite internal standards procedure. The methodology was validated by the accurate analysis of two certificated reference materials (DORM-2 and DOLT-3).

Optimization of operating conditions of axially and radially viewed plasmas for the determination of trace element concentrations from ultrasound-assisted digests of soil samples contaminated by lead pellets

The method of ultrasound-assisted extraction followed by inductively coupled plasma optical emission spectrometry (ICP-OES) used for the determination of trace element concentrations (arsenic, copper, lead, antimony, and zinc) in shooting range areas was optimized. Optimization was achieved not only on the basis of the analysis of appropriate standard reference materials but also on that of 31 synthetic mixtures of matrix and analyte elements (aluminum, antimony, arsenic, calcium, copper, lead, iron, manganese, silicon, and zinc), in five concentrations. All the measurements were performed in robust plasma conditions which were tested by measuring the Mg II 280.270 nm/Mg I 285.213 nm line intensity ratio. The highest Mg II 280.270 nm/Mg I 285.213 nm line intensity ratios were observed when a nebulizer gas flow of 0.8 L min −1, auxiliary gas flow of 0.2 L min −1 and plasma power of 1400 W were used for both the axially and radially viewed plasmas. The analysis of 31 synthetic mixtures of the selected elements showed that As concentrations could be accurately determined with axially viewed plasma alone. The determination of Pb and Sb could be performed with either axially or radially viewed plasma whereas, surprisingly, Cu could be determined with high accuracy using radial plasma alone with a power of 1400 W. All the elements investigated were determined with high accuracy using robust plasma conditions and a combination of axially and radially viewed plasmas. The total recoveries of elements from SRM 2710 (Montana soil) and SRM 2782 (Industrial sludge) were highly comparable to leach recoveries certified by the National Institute of Standards and Technology (NIST).

A component test facility based on the spherical tokamak

Recent experiments (Synakowski et al 2004 Nucl. Fusion 43 1648, Lloyd et al 2004 Plasma Phys. Control. Fusion 46 B477) on the Spherical Tokamak (or Spherical Torus, ST) (Peng 2000 Phys. Plasmas 7 1681) have discovered robust plasma conditions, easing shaping, stability limits, energy confinement, self-driven current and sustainment. This progress has encouraged an update of the plasma conditions and engineering of a Component Test Facility (CTF), (Cheng 1998 Fusion Eng. Des. 38 219) which is a very valuable step in the development of practical fusion energy. The testing conditions in a CTF are characterized by high fusion neutron fluxes Γn ≈ 8.8 × 1013 n s−1 cm−2 (‘wall loading’ WL ≈ 2 MW m−2), over size-scale >105 cm2 and depth-scale >50 cm, delivering >3 accumulated displacement per atom per year (‘neutron fluence’ >0.3 MW yr−1 m−2) (Abdou et al 1999 Fusion Technol. 29 1). Such conditions are estimated to be achievable in a CTF with R0 = 1.2 m, A = 1.5, elongation ∼3, Ip ∼ 12 MA, BT ∼ 2.5 T, producing a driven fusion burn using 47 MW of combined neutral beam and RF heating power. A design concept that allows straight-line access via remote handling to all activated fusion core components is developed and presented. The ST CTF will test the lifetime of single-turn, copper alloy centre leg for the toroidal field coil without an induction solenoid and neutron shielding and require physics data on solenoid-free plasma current initiation, ramp-up to and sustainment at multiple megaampere level. A systems code that combines the key required plasma and engineering science conditions of CTF has been prepared and utilized as part of this study. The results show high potential for a family of relatively low cost CTF devices to suit a range of fusion engineering and technology test missions.

Fusion Engineering and Plasma Science Conditions of Spherical Torus Component Test Facility

A broadly based study of the fusion engineering and plasma science conditions of a Component Test Facility (CTF), using the Spherical Torus or Spherical Tokamak (ST) configuration, have been carried out. The chamber systems testing conditions in a CTF are characterized by high fusion neutron fluxes Γn > 4.4 × 1013 n/s/cm2, over size scales > 105 cm2 and depth scales > 50 cm, delivering > 3 accumulated displacement per atom (dpa) per year. The desired chamber conditions can be provided by a CTF with R0 = 1.2 m, A = 1.5, elongation ~ 3, Ip ~ 9 MA, BT ~ 2.5 T, producing a driven fusion burn using 36 MW of combined neutral beam and RF power. Relatively robust ST plasma conditions are adequate, which have been shown achievable4 without active feedback manipulation of the MHD modes. The ST CTF will test the single-turn, copper alloy center leg for the toroidal field coil without an induction solenoid and neutron shielding, and require physics data on solenoid-free plasma current initiation, ramp-up, and sustainment to multiple MA level. A new systems code that combines the key required plasma and engineering science conditions of CTF has been prepared and utilized as part of this study. The results show high potential for a family of lower-cost CTF devices to suit a variety of fusion engineering science test missions.

Spherical Tokamak Plasma Science and Fusion Energy Component Testing

Recent progress(1) in plasma science of the Spherical Tokamak (or Spherical Torus, ST)(2) has indicated relatively robust plasma conditions in a broad number of topical area including strong shaping, stability limits, energy confinement, self-driven current, and sustainment. This progress has enabled an extensive update of the plasma science and fusion engineering conditions of a Component Test Facility (CTF)(3), which is potentially a necessary step in the development of practical fusion energy. The chamber systems testing conditions in a CTF are characterized by high fusion neutron fluxes n > 4.4 1013 n/s/cm2, over sizescale > 105 cm2 and depth-scale > 50 cm, delivering > 3 accumulated displacement per atom (dpa) per year(4). Such chamber conditions are calculated to be achievable in a CTF with R0 = 1.2 m, A = 1.5, elongation ~ 3, Ip ~ 9 MA, BT ~ 2.5 T, producing a driven fusion burn using 36 MW of combined neutral beam and RF power. The ST CTF will test the life time of single-turn, copper alloy center leg for the toroidal field coil without an induction solenoid and neutron shielding, and require physics data on solenoid-free plasma current initiation, ramp-up, and sustainment to multiple MA level. A newmore » systems code that combines the key required plasma and engineering science conditions of CTF has been prepared and utilized as part of this study. The results show high potential for a family of relatively low cost CTF devices to suit a range of fusion engineering science test missions.« less