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In the later 1800s a new form of popular literature, juvenalia, emerged to cater to children as programmes of universal literacy were put in place throughout the industrialised world. This had its greatest impact on the transatlantic English-speaking world. British writers such as G. A. Henty romanticised views of life on the imperial frontier and became massively popular in America. By 1900 American juvenalia was beginning to favour imperial world views, in particular in many of the several thousand titles published by the Stratemeyer Syndicate. Such juvenalia ‘educated’ teenagers, boys especially, in their responsibilities to their society and persuaded American boys to support imperialism, in particular by focusing on the exciting role of new technologies in militarism. Victorian and Edwardian juvenalia are filled with optimism and such new technologies as airplanes and submersibles were seen as the solution to many geopolitical problems. Such optimism faded with the appalling experiences of World War I. In the 1920s Hollywood movies such as Wings and Hells’s Angels began to romanticise such air combat. In Britain Captain W. E. Johns responded negatively. Johns’ view of the technologies, expressed through the experiences of his main character, Biggles, and based on his own air combat experience in the war, was realistic and well aware of their deadly nature. The Biggles novels also clearly encouraged air policing of the Empire. American pulp magazines and novels continued to romanticise air war but by the early 1930s they had exhausted wartime topics and began to focus on the building Japanese threat. As an American ‘Empire’ developed in the period between World Wars I and II it focused heavily on the Pacific and the growth of American geopolitical interests there. L. Ron Hubbard’s many novels of aerial warfare are about America’s need to support China against Japanese aggression. Both British and American juvenalia culturally conditioned their country’s young males to fight what both authors clearly saw would be the next aerial war.

The realization of power from Magnetic Confinement Fusion is presently following a plan that will span several decades. The mainstream route is via ITER, combined with, or followed by, materials de...

In 1913 the Daily Mail offered a substantial prize for the first transatlantic flight. The first flights occurred in 1919. Twenty years later the route's first commercial heavier-than-air service opened. The path from 1913 to 1939 was technologically challenging, but rewarding since it sped up connections between London and the emerging second trading state financial centre of New York. Civil aviation was closely linked to the technologies needed for strategic bombing and long range maritime air patrols. Such technologies emerged first in Imperial Germany although from British theoretical roots, then from developments at the National Advisory Committee on Aeronautics, all of which spread widely in the late 1920s.

Walter Johnson. Cambridge, MA: Belknap, 2013. 526 pp., illusrations, tables, notes, index. $35.00 cloth (ISBN 978-0-674-04555-2).Roger G. Kennedy. Norman, OK: University of Oklahoma Press, 2013. xv...

Douglas R. Burgess Jr. Stanford, CA: Stanford University Press, 2016. viii and 342 pp., notes, bibliography, index. $35.00 cloth (ISBN 9780804798068).Gone now, and increasingly forgotten with the e...

Halford Mackinder has had a posthumous existence that many of us might envy. Long after his earthly demise, some of his ideas, particularly that of the “geographical pivot of history,” keep coming back to life. Currently, some well-known pundits in US foreignpolicy circles, typically thought of as neo-conservative and keen on a “muscular” US military presence around the world, have re-discovered Mackinder’s geographical determinism as providing a seemingly naturalistic account for the approaching rebirth of the “yellow peril” (the rise of China) and offering as it did at the turn of the last century a timeless rendering of the challenges to the democratic maritime powers from the despotic land powers of Eurasia. The widely cited American journalist Robert Kaplan (2010: 22), for example, frames the emerging “geography” of China’s power almost entirely in these terms. It is timely, therefore, to have a new intellectual biography of Mackinder that not only critically engages with the central themes of his geopolitics but that does so by both situating them in the historical context of the early twentieth century and showing why they remain attractive in some quarters by dint of their effective depoliticization of the very world politics that they underwrite. This book matters, therefore, in a number of distinctive ways. That was why a session devoted to it was so worth organizing at the Washington DC AAG Annual Meeting in April 2010.

This paper creates a traditional, counterfactual, historical geography that proposes the rise of an American Empire in the 1800s instead of the British. The industrialization of the British world-economy of the early 1800s, victory in the Napoleonic Wars, and the consequent success of the British Empire fundamentally depended on cotton textiles, thus on American cotton agriculture. Cotton was, to the economies of the nineteenth century, very much like oil is to those of the late twentieth and early twenty-first enturies. The development of the American cotton South after 1800 was based heavily on the reproduction of slaves within the South. Had Jefferson ended slavery, as he at one time considered, I suggest that an alternative America would have arisen in which Jeffersonian idealism would have encouraged family farms as the principal units of agricultural production. I further argue that, absent the availability of cheap British manufactures, the Philadelphia School of Protectionists would also have likely triumphed early and an American industrial development based on internal growth fueled by cotton grown on family farms would have allowed America to come to dominate the world-economy of the late 1800s. Protectionist policies would have similarly excluded French manufactures and the industrial development based on cotton the French were also attempting in the late 1700s would have failed just as did that of Britain. French military victory in the Napoleonic Wars would not have produced a French world-economy. An America without serious global opposition would not have resisted annexing all of Mexico and Canada in the 1840s and expanding aggressively into Asia via the Pacific basin and Hawaii to create an American Empire.

MR sialography using heavily T(2) weighted projection techniques relies upon saliva for image contrast, and the visualization of normal ducts is often limited. Methods used to increase the volume of intraductal saliva during imaging in order to improve duct visualization have not been previously evaluated. The effect of a sialogogue and passive ductal occlusion on the ability to visualize the main and intraglandular salivary gland ducts during MR sialography was investigated. Three-dimensional (3D) T(2) weighted MR sialograms were obtained from 12 healthy volunteers with and without the combined use of a sialogogue and passive ductal occlusion pad adjacent to the parotid duct orifice on one side. Two radiologists (in consensus) subjectively evaluated ductal visualization and image artefacts on the resulting blinded maximum intensity projections. The results demonstrate that main duct visualization was significantly improved (p0.00001) by this technique, with no significant change seen in image artefacts. Although an improvement in intraglandular duct visualization was noted, this was not statistically significant (p = 0.05). Thus, the use of a sialogogue and passive ductal occlusion improves visualization of the main parotid duct in volunteers undergoing MR sialography. Further optimization and evaluation of this approach should lead to improvements in the MR sialography examination of patients.

In the period leading up to World War I, roughly the British Edwardian period, international relations shifted with great rapidity, making this one of the most significant transitional periods in world history. Two polities, the United States and imperial Germany, pulled level with Great Britain on the world stage and began to challenge British primacy for two main reasons. Both began this drive in the 1860s. Once in charge of Congress, in 1862 the American Republican Party declared a form of economic "war" on Great Britain by passing a stiff protectionist tariff against largely British manufacturers. Paul Kennedy dated the start of the Anglo-German rivalry in the early 1860s as coming from "different perceptions of how domestic policies and external strategies should be arranged" (1980, 8). Imperial Germany imposed its own protectionist tariff in 1879. Both challenger polities, their economies driven increasingly by the second industrial revolution and protected behind increasingly steep tariff walls, began to challenge the global manufacturing dominance Great Britain had achieved in the first industrial revolution. Both began to reach economic parity with Great Britain in the 1880s. The second challenge came through global power projection. In the 1880s neither the United States nor imperial Germany could project power globally, because neither had a blue-water battle fleet. Alfred Thayer Mahan's work on the link between seapower and history made a very clear case that the only way to global power was to have a blue-water battle fleet (1890, 1892), and both Germany and the United States took notice. In the United States Theodore Roosevelt wrote approvingly to Mahan within forty-eight hours of his first book's publication and, in Atlantic Monthly, he published one of the first reviews of Mahan's work (Karsten 1971, 589). As president (1901-1909), Roosevelt oversaw the creation of the United States's first global battle fleet. In Germany Kaiser Wilhelm noted in 1894, "I am ... not reading but devouring Captain Mahan's book.... It is on board all my ships and constantly quoted by all my captains and officers" (quoted in Herman 2004, 474). German actions followed in 1898, with the passing of the First Navy Law to build a High Seas Fleet that also became known as the "Risk Fleet," a fleet powerful enough to ensure that Great Britain would not risk war with Germany. The Second Navy Law of 1900 doubled the size of the German fleet (Hobson 2002, 7). "No issue was as likely to turn Great Britain into an implacable adversary as a threat to its command of the seas," yet the navalist pressure groups in Germany "developed a vested interest in tensions with Great Britain to justify naval appropriations" and used the series of crises in odd parts of the globe from Samoa on to do precisely that (Kissinger 1994, 185). Both economic and military challenges to primacy are conventional parts of international relations theory and well understood. Aaron Friedberg elaborated these in The Weary Titan as challenges based on shifts in relative economic power, financial power, sea power, and land power, all forms of calculative or "hard" power (1988). But this transitional period also saw a third challenge, one that arose out of perceptual or "soft" power: the extent to which a given polity could be said to have a "will to power." Great Britain had long had a clear will to power, and a key, but generally seriously understated, element of international relations theory is the extent to which this was lost by Great Britain in the late 1800s at the same time as it was being gained by the United States and imperial Germany. After summarizing the various realist theories, Friedberg noted that they "leave important unanswered questions. What are the internal characteristics that determine how a state will respond to external pressures?" (p. 6). In the perceptual model of power, "statesmen are seen to deal in less precise but more lingering images, both of other countries and of their own . …

This paper deals with one component of one of the major aspects of hegemonic competition, technological change achieved largely through technology transfer, in this case in the chemical industry. It deals with how the new technology of organic chemistry was created and encouraged in the late 1800s by the global textile industry's need for dyestuffs; how that technology, though invented in Britain, was developed in Germany; and how that technology was finally successfully transferred to America once its central importance to the production of explosives became obvious in World War I. It follows the argument developed by Hugill (1988, 1993) that a switch began in the late 1800s from one form of capitalist world economy to another: from one in which agro-industrial supremacy was what mattered—the argument of Wallerstein (1984)—to one in which techno-industrial supremacy became the main route to the efficiencies demanded by hegemony. It also follows Hugill's argument that software innovations in the way work is done are often more important for success in the world economy than the hardware innovations of what is actually produced (Hugill, 1993). What made the switch from the agro- to the techno-industrial world economy possible was innovation and technology transfer across a wide range of activities, although some technologies turned out to be much more critical than others.

We report on studies of detached plasma operation in the UMIST linear system (ULS). The ULS, designed to study a range of edge physics issues relevant to tokamak divertors, is capable of producing plasmas with electron densities and temperatures in the range 10 17 –10 19 m −3 and 2–15 eV, respectively. Previous studies of the interaction between the hydrogen plasma and low-pressure hydrogen gas have identified a regime where molecular activated recombination (MAR) processes dominate plasma losses. Here we report on studies in which the upstream plasma parameters are varied such that three-body and radiative electron–ion recombination (EIR) dominates. Initial modelling of the recombination region is undertaken using a simplified version of the one-dimensional electron energy and continuity equations. We determine the factors that govern the threshold between MAR and EIR dominated detached regimes in terms of upstream plasma parameters and compare this with predictions based on the competing effects of electron cooling and recombination.

Technology is the motor of capitalist devel- opment, the mechanism Schumpeter described that creates gales of creative destruction in the capitalist world system, but that allows capitalism to restore profitability through new investment, be self- replicating, and thus not be subject to Marx's Law of the Tendency of the Rate of Profit to Fall. Such creative destruction occurs cycli- cally, as suggested by Kondratiev. Innovation, denovation, and the diffusion of both are central processes to both Kondratiev and heg- emonic or world leadership cycles, which extend over two Kondra- tiev cycles. Innovation occurs in innovation milieus, usually very complex urban regions, and is rare and difficult to manage. Some innovations are shown to drive Kondratiev upswings and hegem- onic cycles much more than others. Denovation and the deindus- trialization attendant on this part of the process of creative destruc- tion is much less studied. The diffusion of innovation is more than innovation, but is controlled by adoption environment and the sta- tus of the sender, or geltung. Two types of technology transfer are examined—hardware and software—within two geopolitical are- nas—trading polities and territorial polities. Hardware technolo- gies that deal with material production are distinguished from those that deal with cultural production.

This paper examines individual voter turn-out and its putative relationship with voting outcomes at the voting precinct level. Via a GIS-based address matching procedure, we were able to georeference individual voters (registered voters who casted their votes) and non-voters (those registered voters who did not cast their votes) for three recent local referenda in College Station, Texas. We then conducted a scale-sensitive, second-order spatial analysis for the spatial distribution of voter turn-outs, followed by a spatial clustering analysis of the voting results using Getis–Ord’s G i statistic. We found that the extent of neighborhood effects in local elections is heavily influenced by the voter turn-out. If voter turn-out is clustered at intermediate and large scale, voting results tend to be clustered and also exhibit a sharp polarization between high and low values. If voter turn-out tends to be uniform/regular at intermediate scales but randomly distributed at both small and large scales, there appears to be less clustering in the voting results and thus lack of the neighborhood effect. If the voter turn-out pattern is mixed-uniform/regular at the small scale, random at the intermediate scale, but clustered at the large scale, the voting results show a stronger neighborhood effect.

Tokamak Energy Ltd, UK, is developing spherical tokamaks using high temperature superconductor magnets as a possible route to fusion power using relatively small devices. We present an overview of the development programme including details of the enabling technologies, the key modelling methods and results, and the remaining challenges on the path to compact fusion.

(2011). Geopolitics and Empire: The Legacy of Halford Mackinder. By Gerry Kearns. Geographical Review: Vol. 101, No. 2, pp. 285-287.

Nitrogen plasmas at atmospheric pressure produced by 2.45 GHz microwaves at a power density of approximately 10 MW m-3 have a degree of ionization less than about 10-7. Nevertheless they have interesting and potentially important effects on polymer and metal surfaces exposed to them. An experimental programme is underway to identify the active species in the plasma and its afterglow. This paper describes a simplified model of the chemical kinetics in the plasma that allows species concentrations to be estimated in a range of conditions, for comparison with experimental data. It predicts a high degree of dissociation combined with low gas temperature in microwave-generated plasmas.

Experimental data on the transition from the low to high confinement mode in tokamaks is briefly reviewed, concentrating on those cases where the transition is made by a slow change in external parameters. The first H-modes, which occurred after the sudden application of neutral beam heating, appeared to result from a bifurcation of the edge transport. However, slow transitions produced, for example, by ohmic heating do not have the character of a bifurcation but appear to result from a slow and reversible change in the characteristics of the edge turbulence, which becomes increasingly intermittent as the high confinement mode is approached. The experimental results are interpreted in the light of various models of the transition process and of the type III or transition edge localized modes that accompany it. The evidence is mainly against the bifurcation hypothesis but nonlinear processes are clearly involved. The implications for the next generation of tokamaks intended to reach thermonuclear ignition are discussed

We describe an experiment, the UMIST Linear System (ULS), in which a hydrogen plasma stream, guided by a longitudinal magnetic field, is injected through a diaphragm containing an orifice into a separately-pumped target chamber in which the neutral hydrogen pressure can be raised to a maximum of 8 mTorr. The stream is about 6 mm in diameter, has an electron temperature of up to 15 eV and an ion flux of 3×1018 s-1; it is supersonic with Mach number up to M≈3. We have studied both the passage of the stream through the orifice and the interaction of the supersonic plasma with neutral hydrogen in the target chamber. We find that transmission is incomplete even when the orifice diameter is five times that of the plasma; we attribute this to the presence of ion trajectories which extend well outside the visible plasma and are intercepted by the diaphragm. In the target chamber, the stream does not broaden, but the ion flux decreases approximately exponentially with distance, with a scale length of the order of the mean free path for momentum transfer in ion-neutral collisions, and much less than that expected for other processes, such as charge exchange or electron-ion recombination. Elastic collisions alone cannot decrease the flux, but would lead to a large accumulation of slow ions in thermal equilibrium with the neutral gas, which must be limited by some other loss process: collisional diffusion and electron-ion recombination are too slow, leading to a density approaching 1020 m-3. The observed density is of the order of 1018 m-3, requiring a process with a rate of 10-100 times faster. Calculated rates for molecular-activated recombination (MAR) of the slow ions are of this order, and the predicted density agrees with our observations to order of magnitude.

A plasma with a volume of 10-4 m3 and a very low degree of ionization can be maintained inside a high-Q cavity using up to 1.4 kW of microwave power at 2.45 GHz. Various working gases have been employed, including air, nitrogen and noble gases at pressures up to 2 × 105 Pa. The reported results are for nitrogen at atmospheric pressure. The plasma absorbs about 80% of the incident power implying a mean root mean square electric field in the cavity for plasma maintenance of 50 kV m-1 , which is much smaller than that required for breakdown. Estimates of the mean heavy species temperature from the form of the band spectra at 315 and 340 nm give approximately 2200 K. The electron collision frequency and the ratio E /N are 4 × 1011 s-1 and 1.5 × 10-20 V m2 , respectively. Since the electron collision rate is much higher than the microwave frequency, previous results for a dc electric field obtained by Engelhardt et al can be used to infer a characteristic electron energy of 1.1 eV, with a strongly non-Maxwellian distribution function, and an electron density of 7 × 1016 m-3 . A substantial fraction of the input power is transferred from electrons to the heavy species by inelastic collisions, principally due to the excitation of molecular vibration.

After 1870 mass education and the rise of mass literacy began to create a huge market for juvenile literature in the industrial world in the form of weekly papers and novels. Sales in the tens of millions were realized by some authors. By the early twentieth century this market had matured, gendered, segmented, and regionalized. British boys’ juvenile novels from such authors as Henty stressed the link between manliness, sports, communal and Christian responsibility and empire. The empire was the dominant site of individual social advancement. Sexuality was to be deferred until marriage. American juveniles from such authors as Stratemeyer stressed manliness, individuality, teamwork, the Anglo-Saxon compact and technology. Technology was the dominant site of individual social advancement. With the Spanish-American War American boys’ juveniles started to teach that, contrary to America’s past stand against imperialism, America had a moral right to become an imperial power and should learn such behaviour from Britain. From 1898 to 1912 American juveniles taught that, as Britain declined, America was shifting from the junior to the senior partner in the Anglo-Saxon compact.

At Versailles in 1919 President Wilson described three arenas of economic struggle, mediated by technology and geopolitics, that he saw developing between America and Britain as a new international order emerged: struggles over international transportation, petroleum, and international communication. The case of international transportation, almost all of it maritime in the 1920s, is intimately connected with that of the problem many observers saw with an insecure and possibly faltering global supply of petroleum. America dominated the early period of global petroleum supply, especially after the strike at Spindletop in Texas in 1901, but Spindletop was faltering by 1920. Even before World War One broke out German and British War Aims thus began to focus on the likely oil reserves of the Middle East that America could not control, Germany via the mineral rights the company was granted along the line of the Berlin to Baghdad Railway concession of 1903 and Britain via the Sykes-Picot-Sazanoff agreement of 1916, the latter resulting in the eventual creation of Iraq. In the run-up to the war oil-firing of steam turbine engine warships was seen as a technology that would substantially increase the fighting capacity of naval vessels through, amongst other things, radically easier refueling and a substantial reduction in stokehold crew size. Operators of merchant vessels followed a similar line of reasoning for a new generation of steam turbine powered ships coming to dominate the Atlantic shuttle by virtue of their speed. The war, however, proved a huge technology forcer in the area of diesel engines, which even in their early form were ideally suited to powering merchant ships, offering substantial savings in fuel and/or labor costs over steamships. Commentators in the 1920s were very clear on the relationship between the petroleum and marine transportation struggles, arguing that whoever controlled the right mix of marine transportation technology, in particular that of the merchant marine, and petroleum supply would control the emerging post-war international order. Of the major powers neither Britain nor Germany did particularly well in shifting their merchant marines to diesel power, America did very poorly. America’s strength was in continuing to control the global oil supply.

Monte Carlo modelling of plasma extinction by neutral particles requires energy and momentum sinks to be determined with sufficient statistical significance. We focus on this aspect using calculations of an idealized 1D plasma-gas interface with the Eirene code. A novel non-linear version including self-collisions amongst neutral particles is also applied to admit gas viscosity. It emerges that statistically significant momentum losses often cannot practicably be determined, even at modest plasma temperatures (∼ 10 eV), using conventional collision-estimator techniques. Gas viscosity effects also tend to inhibit extraction of plasma momentum and hinder extinction. Certain possibilities to improve numerical methods are mentioned.

In their pioneering paper [1] Stambaugh et al developed the Peng-Hicks concept [2] of a fusion reactor based on a solid copper centre-post Spherical Tokamak (ST). Using the promising results from the START experiment [3], they produced a vision for a path to Fusion Power. This path had two elements: the ability to produce high fusion gain from an ST, and equally importantly, the ability to demonstrate this in a small (and therefore low cost) pilot plant device. In this paper we review various attempts to pursue this vision, and try to elucidate why success has not yet been achieved. However we show that the advent of high temperature superconductors (HTS) may overcome some of the problems, and we suggest a revised version of the small, low entry cost route to Fusion Power.

A description of the various ELM types observed in single null divertor plasmas in COMPASS-D is given, including type I and type III ELMs in both ECRH and ohmically heated plasmas. Precursor oscillations to both type I and type III ELMs have been observed. The large variation in the precursor mode structure is discussed, as well as models of the effect on the plasma.

In reply to the Comment by Biel et al (2016 Nucl. Fusion 57 038001) on our recent papers Costley et al (2015 Nucl Fusion 55 033001) and Costley (2016 Nucl. Fusion 56 066003), we point out that the fusion triple product, nTτ E, and fusion power gain, Q fus, cannot be expressed solely in terms of independent engineering design variables such as major radius, R, and toroidal field, B; output performance variables such as normalised beta, β N, safety factor, q, and fusion power P fus, have to be invoked. Further, we show that the density limit has the effect of largely cancelling the size dependence in nTτ E and Q fus, which would otherwise be present, when these parameters are expressed in terms of P fus. Considerations of engineering aspects are also briefly discussed.

Single null X-point discharges on COMPASS-D show a gradual L to H transition. Frequent boronization gives long ELM-free H-mode periods, duration > 100 ms, with continuously rising density to > 1.5 × 1010 m−3. The LH transition threshold behaviour is more complex than that predicted by present simple scaling laws, with a well-defined low-density limit being observed and sensitivity to small perturbations at the plasma boundary. Density and recycling behaviour is analysed. In discharges refuelled by recycling alone, the coefficient of recycling as well as the particle confinement time is higher in H-mode periods.

The COMPASS-D tokamak has recently obtained H-mode plasmas in a single-null X-point configuration with no additional heating. Clear H-mode signatures have been observed including reduction in Dalpha light and the unmistakable appearance of ELMs and ELM-free periods. Recycling and gas puff can play crucial roles in achieving and terminating the H-modes. The emergence of distinct ELMs, from the apparently-random fluctuations, of the background Dalpha light, is usually one of progression, taking some 10s of ms rather than a sudden discontinuity. The relatively slow evolution allows for detail examination of important phenomena, such as improvements to confinement and fluid rotation. The H-mode quality improves with density, unless impurity accumulation becomes important. Improvements to the energy and particle confinement are observed and are accompanied by positive increases in the radial electric field at approximately=4 cm inside the last closed flux surface (LCFS). The ohmic powers in discharges with clearly defined H-modes have not been less, so far, than the power obtained from power threshold scalings from larger machines.

Modulated ECRH has been used to study electron thermal transport in DITE. In most cases the spatial structure of the thermal waves produced is consistent with a simple diffusive transport model in which the heat flux is proportional to the electron temperature gradient, q = -ne?e ?Te. At low density (ne ? 1019 m-3) the values of electron thermal diffusivity deduced from modulation experiments (?emod) are ? 2.5 m2.s-1, similar to the values deduced from power balance analysis (?ePB and sawtooth heat pulse propagation (?est). At higher density (ne ? 3 × 1019 m-3) the interpretation of the modulation data is sensitive to details of the ECRH power deposition profile. The high density data are fitted best by assuming that approximately 30% of the ECRH power is deposited with a broad profile with the remainder more localized, in qualitative accordance with ray tracing code predictions. The values of ?emod deduced are then ? 1.3 m2.s-1, again similar to the values of ?ePB and ?est

The START (Small Tight Aspect Ratio Tokamak) experiment became operational in January 1991 at AEA Fusion Culham Laboratory. It is the only tokamak producing hot plasmas at aspect ratios as low as A=R/a approximately 1.3, and is providing valuable insight into the physical processes (such as toroidicity and trapping) involved at low aspect ratio. Three topics are discussed: equilibrium properties, including evidence of neo-classical and bootstrap effects; energy confinement studies; and MHD properties, including possible explanations for the apparent absence of the major disruption at low A.

Low‐aspect‐ratio tokamaks offer both the economic advantage of smaller size and a number of physics advantages which are not available at conventional aspect ratio. The Small Tight Aspect Ratio Tokamak (START) [Fusion Technology 1990, edited by B. E. Keen, M. Huguet, and R. Hemsworth (North‐Holland, Amsterdam, 1991), Vol. 1, p. 353] was conceived as a first substantial test of tokamak plasma behavior at low aspect ratio. It has achieved plasma currents up to 200 kA, peak densities of ∼2×1020 m−3 and central electron temperatures of ∼500 eV at an aspect ratio of 1.3–1.5. Central beta values of ∼13% have been measured and the volume‐averaged beta 〈β〉 can approach the Troyon limit. Plasmas are naturally elongated (κ≲2.0) and are vertically stable without feedback control. Major disruptions have not been observed at low aspect ratios (A≤2.0).

American engineers have moved more earth than any engineers in history. The work of Austrian Karl Terzaghi, the “father of soil mechanics,” was crucial to that ability. Soil mechanics and improvements in earth-moving machinery allowed construction of a national “Good Roads” network in the U.S. beginning in the 1920s. Very serious floods, such as the Mississippi flood of 1927, persuaded Americans to spend much more money on flood control from the 1930s on. The needed levees and earthen dams were feasible only with the new machinery and a thorough understanding of soil mechanics.

Experimental results from the COMPASS-C tokamak reveal a sharp threshold in amplitude above which externally applied static resonant magnetic perturbations (RMPs) induce stationary magnetic islands. Such islands (in particular, m=2, n=1 islands) give rise to a significant degradation in energy and particle confinement, suppression of the sawtooth oscillation and a large change in the impurity ion toroidal velocity. The observed threshold for inducing stationary (2,1) islands is consistent with a phenomenological resistive MHD model which takes into account plasma rotation (including poloidal flow damping) and externally applied resonant fields. Broadly similar results are found for applied fields other than m=2, n=1. Other results from RMP experiments are also discussed, such as the stabilization of rotating MHD activity, stimulated disruptions and extensions to the disruptive density limit. Finally, the likely effect of field errors on large tokamaks is briefly examined in the light of the COMPASS-C results