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An estimated 56% of households in rural India defecated in the open in 2015, making India the most significant contributor to the global sanitation burden. This cross-sectional study uses data collected in 2016 from 499 households in rural Jharkhand to understand the constraints of latrine adoption and drivers of sanitation preferences (plans to adopt toilets and willingness to pay for toilets). Focusing on a region with a large tribal population, the study examines two types of predictors, namely structural factors (objective socioeconomic, sociocultural and ecological characteristics) and psychosocial drivers (perceived unaffordability of toilet, hygiene and sanitation knowledge, perceived health risks, attitudes, both descriptive and injunctive social norms, and perceived water stress). We find that structural constraints related to educational, economic and sociocultural inequalities predict toilet ownership. Low sanitation rates can neither be attributed to a lack of expressed demand nor lack of recognition of the disadvantages of open defecation. Similarly, variations in sanitation preferences are neither explained by differences in hygiene and sanitation knowledge nor by understandings of sanitation health risks. We find that perceived unaffordability, attitudes (perceived benefits of toilet and disadvantages of OD) and perceived descriptive social norms are of key importance. This implies a potential for persuasive strategies that manipulate social norms around sanitation, particularly if they simultaneously address perceptions around financial unaffordability of toilets and around the benefits of toilets. Importantly, however, attempts to change sanitation preferences by acting on forces of social (dis)approval (i.e. through perceived injunctive social norms) may be ineffective and generate negative unintended consequences.

The dependence of the thermal diffusivity on the heat flux has been investigated in JT-60U plasmas by varying the neutral beam power. In positive magnetic shear (PS) plasmas, the ion thermal diffusivity (χi) in the core region generally increases with the heating power, as with the L mode at low heating powers. However, as a result of the intensive central heating, a weak internal transport barrier (ITB) is formed, and the χi value in the core region starts to decrease. Corresponding to a further increase in the heating power, a strong ITB is formed and the χi value is reduced substantially. In the case of reversed magnetic shear (RS) plasmas, on the other hand, no power degradation of the χi value is observed in any of the heating regimes. The electron thermal diffusivity (χe) is correlated with the χi value in PS and RS plasmas. Furthermore, the dependence of the ion thermal diffusivity on the radial electric field (Er) shear has also been investigated. By considering the non-locality in the relation between the Er shear and the χi value, a threshold in the effective Er shear to change the state from a weak to a strong ITB is identified.

The relationship between particle and heat transport in an internal transport barrier (ITB) has been systematically investigated in reversed shear (RS) and high βp mode plasmas of JT-60U. The electron effective diffusivity is well correlated with the ion thermal diffusivity in the ITB region. The ratio of particle flux to electron heat flux, calculated on the basis of the linear stability analysis, shows a similar tendency to an experiment in the RS plasma with a strong ITB. However, the calculated ratio of ion anomalous heat flux to electron heat flux is smaller than the experiment in the ITB region. Helium and carbon are not accumulated inside the ITB even with ion heat transport close to a neoclassical level, but argon is accumulated. The helium diffusivity (DHe) and the ion thermal diffusivity (χi) are 5–15 times higher than the neoclassical level in the high βp mode plasma. In the RS plasma, DHe is reduced from 6–7 times to a 1.4–2 times higher level than the neoclassical level when χi is reduced from 7–18 times to a 1.2–2.6 times higher level than the neoclassical level. The carbon and argon diffusivities estimated assuming the neoclassical inward convection velocity are 4–5 times larger than the neoclassical value, even when χi is close to the neoclassical level. Argon exhaust from the inside of the ITB is demonstrated by applying electron cyclotron heating (ECH) in the high βp mode plasma, where both electron and argon density profiles become flatter. The flattening of the argon density profile is consistent with the reduction of the neoclassical inward convection velocity due to the reduction of the bulk plasma density gradient. In the RS plasma, the density gradient is not decreased by ECH and argon is not exhausted. These results suggest the importance of density gradient control in suppressing impurity accumulation.

The deuterium-tritium (D-T) experimental program on the Tokamak Fusion Test Reactor (TFTR) is underway and routine tritium operations have been established. The technology upgrades made to the TFTR facility have been demonstrated to be sufficient for supporting both operations and maintenance for an extended D-T campaign. To date fusion power has been increased to {approximately}9 MW and several physics results of importance to the D-T reactor regime have been obtained: electron temperature, ion temperature, and plasma stored energy all increase substantially in the D-T regime relative to the D-D regime at the same neutral beam power and comparable limiter conditioning; possible alpha electron heating is indicated and energy confinement improvement with average ion mass is observed; and alpha particle losses appear to be classical with no evidence of TAE mode activity up to the P{sub FUS} {approximately}6 MW level. Instability in the TAE mode frequency range has been observed at P{sub FUS} > 7 MW and its effect on performance is under investigation. Preparations are underway to enhance the alpha particle density further by increasing fusion power and by extending the neutral beam pulse length to permit alpha particle effects of relevance to the ITER regime to be more fullymore » explored.« less

The National Spherical Torus Experiment (NSTX) at Princeton is designed to assess the potential of the low-aspect-ratio spherical torus concept for magnetic plasma confinement. The plasma has been heated by up to 5 MW of neutral beam injection, NBI, at an injection energy of 90 keV and up to 6 MW of high harmonic fast wave, HHFW, at 30 MHz. NSTX has achieved beta T of 32%. A variety of MHD phenomena have been observed to limit eta. NSTX has now begun addressing E scaling, eta limits and current drive issues. During the NBI heating experiments, a broad Ti profile with Ti up to 2 keV, Ti > Te and a large toroidal rotation. Transport analysis suggests that the impurity ions have diffusivities approaching neoclassical. For L-Mode plasmas, E is up to two times the ITER-89P L-Mode scaling and exceeds the ITER-98pby2 H-Mode scaling in some cases. Transitions to H-Mode have been observed which result in an approximate doubling of tE. after the transition in some conditions. During HH FW heating, Te > Ti and Te up to 3.5 keV were observed. Current drive has been studied using coaxial helicity injection (CHI), which has produced 390 kA of toroidal current and HHFW, which has produced H-modes with significant bootstrap current fraction at low Ip, high q and high{sub etap}.

Local thermal particle and energy transport studies of balanced-injection L-mode and Supershot deuterium plasmas with the same toroidal field, plasma current, and neutral beam heating power have been performed on TFTR. The particle transport of He{sup 2+} and electrons following a small helium gas puff and Fe{sup 24+} induced by laser ablation has been examined and compared to the local energy transport characteristics inferred from power balance analysis. All particle perturbation diffusivities are radially hollow and are similar in magnitude and shape to the effective thermal conductivities found by power balance analysis. All particle diffusivities are 1--2 orders of magnitude larger than neoclassical values, except near the magnetic axis. A reduction in the helium diffusivity D{sub He} in the Supershot as compared to the L-mode is accompanied by a similar reduction in the effective single fluid thermal conductivity {chi}fluid. Also, the helium core convective velocity V{sub He} is found to increase in the Supershot over the L-Mode for r/a < 0.5. A quasilinear model of electrostatic drift waves has been used to calculate ratios between particle and energy fluxes in the Supershot. The measured ratios of the helium and iron particle diffusivities are in good accord with predictions, as aremore » predicted ratios of V{sub He}/D{sub He}. Modelling indicates that the similarity in magnitude and profile shape of D{sub He} and {chi}fluid has generally favorable implications for helium ash content in a future fusion reactor. The core convection found in the Supershot increases the helium concentration on axis but does not reduce the plasma reactivity significantly.« less

We have subjected a silica core fiber optic cable to 4 years of low-level neutron and gamma radiation from Princeton`s TFTR controlled fusion experiment The accumulated dose was 200 Gy. As a result of the radiation, we have measured increased attenuations of 100--300 db/km in the visible part of the spectrum, and a decrease of the numerical aperture. An attempt to decrease this damage by photobleaching failed. We argue that this failure is not unexpected, since the rate of damage is so slow and the time scale so long that the self-annealing process keeps the residual damage at the irreducible level seen in other experiments. The implications of these findings for controlled fusion diagnostics during upcoming experiments with highly reactive deuterium-tritium plasmas are discussed.

A transport code (TRANSP) is used to simulate future deuterium-tritium experiments (DT) in TFTR. The simulations are derived from 14 TFTR DD discharges, and the modeling of one supershot is discussed in detail to indicate the degree of accuracy of the TRANSP modeling. Fusion energy yields and {alpha}-particle parameters are calculated, including profiles of the {alpha} slowing down time, average energy, and of the Alfven speed and frequency. Two types of simulations are discussed. The main emphasis is on the DT equivalent, where an equal mix of D and T is substituted for the D in the initial target plasma, and for the D{sup O} in the neutral-beam injection, but the other measured beam and plasma parameters are unchanged. This simulation does not assume that {alpha} heating will enhance the plasma parameters, or that confinement will increase with T. The maximum relative fusion yield calculated for these simulations is Q{sub DT} {approx} 0.3, and the maximum {alpha} contribution to the central toroidal {beta} is {beta}{sub {alpha}}(0) {approx} 0.5%. The stability of toroidicity-induced Alfven eigenmodes (TAE) and kinetic ballooning modes (KBM) is discussed. The TAE mode is predicted to become unstable for some of the equivalent simulations, particularly after the terminationmore » of neutral beam injection. In the second type of simulation, empirical supershot scaling relations are used to project the performance at the maximum expected beam power. The MHD stability of the simulations is discussed.« less

High resolution ECE and X-ray image reconstructions have been made simultaneously during the sawtooth crash in the fast rotating plasma on TFTR. The X-ray tomography is found not the represent flux surfaces but to show metal impurity behavior. The experimental results show that the reconnection process cause the sawtooth crash, even when the crash time is 20 times faster than the Kadomtsev reconnection time. New features are observed during the sawtooth crash, such as an oval shaped hot spot and a cooler region between the island and the hot spot. 18 refs., 5 figs.

Transport of iron in TFTR discharges is studied by spatially-resolved charge exchange recombination spectroscopy in the visible region of the spectrum. Time evolutions of the densities of Fe{sup 24+} and Fe{sup 23+} ions following injection of iron are modeled by the neoclassical flux plus a moderately hollow diffusivity increasing linearly from 1.3 m{sup 2}/sec on axis to 2.4 m{sup 2}/sec at the plasma edge. For r/a{gt}0.5. the iron diffusivity is significantly smaller than the helium diffusivity measured in identical discharges, while it is larger in the region immediately surrounding the plasma axis. 15 refs., 3 figs.

The diagnostic instrumentation on TFTR (Tokamak Fusion Test Reactor) and the specific properties of each diagnostic, i.e., number of channels, time resolution, wavelength range, etc., are summarized in tables, grouped according to the plasma parameter measured. For comparison, the equivalent diagnostic capabilities of JET (Joint European Torus) and the Japanese large tokamak, JT-60, as of late 1987 are also listed in the tables. Extensive references are given to publications on each instrument.

TSTR (Tokamak Fusion Test Reactor) has operated since December 1982 with ohmically heated plasmas. Routine operation with feedback control of plasma current, position and density has been obtained for plasmas with Ip800 kA, a = 68 cm, R = 250 cm, and Bt=27 kG. A maximum plasma current of 1 MA was achieved with q2.5. Energy confinement times of ~150 msec were measured for hydrogen and deuterium plasmas with e = 2 x 1013 cm-3, Te(0) 21.5 keV, Ti(0) = 1.5 keV and Zeff1 3. The preliminary results suqgest a size-cubed scaling from PLT, and are consistent with Alcator C scaling where T ~ nR2a. Initial measurements of plasma disruption characteristics indicate current decay rates of ~ 800 kA in 8 ms which is within the TFTR design requirement of 3 MA in 3 ms.

The carbon concentration in the central region of TFTR discharges with high power neutral beam heating has been measured by charge-extracted recombination spectroscopy (CXRS) of the C{sup +5} n = 3--4 transition in the extreme ultraviolet region. The carbon concentrations were deduced from absolute measurements of the line brightness using a calculation of the beam attenuation and the appropriate cascade-corrected line excitation rates. As a result of the high ion temperatures in most of the discharges, the contribution of beam halo neutrals to the line brightness was significant and therefore had to be included in the modeling of the data. Carbon concentrations have been measured in discharges with I{sub p} = 1.0-1.6 MA and beam power in the range of 2.6-30 MW, including a number of supershots. The results are in good agreement with carbon concentrations deduced from the visible bremsstrahlung Z{sub eff} and metallic impurity concentrations measured by x-ray pulse-height analysis, demonstrating the reliability of the atomic rates used in the beam attenuation and line excitation calculations. Carbon is the dominant impurity species in these discharges; the oxygen concentration measured via CXRS in a high beam power case was 0.0006 of n{sub e}, compard to 0.04 for carbon. Trends with I{sub p} and beam power in the carbon concentration and the inferred deuteron concentration are presented. The carbon concentration is independent of I{sub p} and decreases from 0.13 at 2.6 MW beam power to 0.04 at 30 MW, while the deuteron concentration increases from 0.25 to 0.75 over the same range of beam power. These changes are primarily the result of beam particle fueling, as the carbon density did not vary significantly with beam power. The time evolutions of the carbon and deuteron concentrations during two high power beam pulses, one which exhibited a carbon bloom and one which did not, are compared. 30 refs., 12 figs., 2 tabs.

A new phenomenon has been observed in TFTR discharges with neutral beam injection and slowly ramped plasma current. When q/sub /psi// (a) reaches certain values close to low-order rational numbers, the D/sub ..cap alpha../ emission decreases and the electron density profile broadens and increases, similar to observations during the H-mode in other tokamaks. This ''q-mode'' appears to have a neutral beam power threshold of /approximately/ 6 MW. During co-injection, the plasma toroidal rotation decreases by /approximately/ 50% at the transition. Very slowly toroidally rotating coherent adge modes, which slow and lock at the transition, were identified from the measured perturbations in /tilde B//sub theta// with mn /approximately/ q/sub /psi//(a). Calculations based on a tearing-mode model indicate that large islands, consistent with these measurements, could be present in the plasma edge and alter the plasma limiter interaction. At the transition Z/sub eff/ increases typically from 3 to 3.5. This increase and the electron density increase are caused largely by an increase in the carbon density. These increases raise the drag on fast ions, rapidly thermalizing some of the energy stored by beam ions, causing a transient rise in the plasma thermal energy. In addition, the global energy confinement time increases transiently.more » 26 refs., 7 figs., 1 tab.« less

Neutral-beam-heated plasmas in TFTR show evidence of substantial non-ohmically-driven toroidal current, even for balanced beam momentum input. The observations are inconsistent with calculations including only ohmic and beam-driven currents, and presently can only be matched by models including the neoclassical bootstrap current. 28 refs., 9 figs., 1 tab.

Compound sawtooth activity has been observed in ohmically heated, high current, high density TFTR plasmas. Commonly called ''double sawteeth,'' such sequences consist of a repetitive series of subordinate relaxations followed by a main relaxation with a different inversion radius. The period of such compound sawteeth can be as long as 100 msec. In other cases, however, no compound sawteeth or bursts of them can be observed in discharges with essentially the same parameters.

ICRF power levels of up to 2.8 MW were achieved during the 1988 experimental run on TFTR. The central metal impurity concentrations (Ti, Cr, Fe, Ni) and Zeff were monitored during ICRF heating by X‐ray pulse height analysis and UV spectroscopy. Antenna phasing was the key variable affecting IRF performance. No increase in metalic impurities was observed for P

Experiments with plasmas having nearly equal concentrations of deuterium and tritium have been carried out on TFTR. To date, the maximum fusion power has been 10.7 MW, using 39.5 MW of neutral-beam heating, in a supershot discharge and 6.7 MW in a high-{beta}{sub p} discharge following a current ramp-down. The fusion power density in the core of the plasma has reached 2.8 MWm{sup {minus}3}, exceeding that expected in the International Thermonuclear Experimental Reactor (ITTER). The energy confinement time, {tau}{sub E}, is observed to increase in D-T, relative to D plasmas, by 20% and the n{sub i}(O){center_dot}{tau}{sub E} product by 55%. The improvement in thermal confinement is caused primarily by a decrease in ion heat conductivity in both supershot and limiter-H-mode discharges. Extensive lithium pellet injection increased the confinement time to 0.27 s and enabled higher current operation in both supershot and high-{beta}{sub p} discharges. First measurements of the confined alpha particles have been performed and found to be in good agreement with TRANSP simulations assuming classical confinement. Measurements of the alpha ash profile have been compared with simulations using particle transport coefficients from helium gas puffing experiments. The loss of energetic alpha particles to a detector at the bottom ofmore » the vessel is well described by the first-orbit loss mechanism. No loss due to alpha-particle-driven instabilities has yet been observed. ICRF heating of a D-T plasma, using the second harmonic of tritium, has been demonstrated. D-T experiments on TFTR will continue both to explore the physics underlying the ITER design and to examine some of the physics issues associated with an advanced tokamak reactor.« less