Design of the national compact stellarator experiment (NCSX)

Results of a detailed and integrated study of compact stellarator configurations as fusion power plant, ARIES-CS, are reported in this paper. The first major goal of the ARIES-CS research was to investigate whether stellarator power plants can be made to be similar in size to advanced tokamak variants. We focused our analysis on quasi-axisymmetric (QAS) configurations as they are able to operate at a low plasma aspect ratio (~4-5). Our efforts to reduce α-particle loss rate-led to new criteria for optimizing QAS configuration. We also developed a non-uniform blanket and a WC-shield, optimized to provide shielding comparable to a regular breeding module but with a much reduced (~ 30%) radial thickness. The total tritium breeding including all modules is ~1.1. The second major goal od the study was to understand and quantify, as much as possible, the impact of complex shape and geometry of fusion core components. It became evident early on that the 3-D shape of the plasma and the coil (and the components between them) necessitates 3-D analyses of various components-typical correlations and insight developed for axisymmetric fusion devices are not appropriate for stellarator geometry. As such, we directly used 3-D CAD models in many of our analyses. Moreover, we found that the results are quite sensitive to the details of 3-D shape of components and slight variations can result in substantial changes. Finally, we have found that engineering configuration as well as assembly/maintenance procedures are key elements in optimizing a compact stellarator-in some cases, these issues determine the choice of technologies. Examples include the selected port-based maintenance scheme which requires a compatible internal design of the fusion core and led to the choice of a ferritic-steel, dual-coolant blanket; and the irregular shape of the superconducting coil that necessitates development of inorganic insulators for highfield magnets. In this paper, trade-offs among physics and engineering constraints are highlighted; key design features and analyses are described; and the major R&D issues are discussed.

2008

An integrated study of compact stellarator power plants, ARIES-CS, has been conducted to explore attractive compact stellarator configurations and to define key research and development (R&D) areas. The large size and mass predicted by earlier stellarator power plant studies had led to cost projections much higher than those of the advanced tokamak power plant. As such, the first major goal of the ARIES-CS research was to investigate if stellarator power plants can be made to be comparable in size to advanced tokamak variants while maintaining desirable stellarator properties. As stellarator fusion core components would have complex shapes and geometry, the second major goal of the ARIES-CS study was to understand and quantify, as much as possible, the impact of the complex shape and geometry of fusion core components. This paper focuses on the directions we pursued to optimize the compact stellarator as a fusion power plant, summarizes the major findings from the study, highlights the key design aspects and constraints associated with a compact stellarator, and identifies the major issues to help guide future R&D.

Fusion Engineering and Design, 2007

This paper summarizes the key engineering outcomes from the ARIES-CS study. The most promising power plant concept is described. The engineering design of the fusion power-core components (including the blanket and divertor) and the coil structural design are briefly described along with a summary of the key results from the detailed neutronics, stress, thermal-hydraulic and power cycle analyses performed in support of the design. The preferred port-based maintenance scheme is summarized. The key stellarator-specific challenges affecting the design are highlighted, including the impact of the minimum plasma-coil distance, the coil design requirements and the need for alpha power accommodation.

Over the past 2-3 decades, stellarator power plants have been studied in the U.S., Europe, and Japan as an alternate to the mainline magnetic fusion tokamaks, offering steady state operation and eliminating the risk of plasma disruptions. The earlier 1980s studies suggested large stellarators with an average major radius exceeding 20 m. The most recent development of the compact stellarator concept delivered ARIES-CS -a compact stellarator with 7.75 m average major radius, approaching that of tokamaks. For stellarators, the most important engineering parameter that determines the machine size and cost is the minimum distance between the plasma boundary and mid-coil. Accommodating the breeding blanket and necessary shield within this distance to protect the ARIES-CS superconducting magnet represents a challenging task. Selecting the ARIES-CS nuclear and engineering parameters to produce an economic optimum, modeling the complex geometry for 3-D nuclear analysis to confirm the key parameters, and minimizing the radwaste stream received considerable attention during the design process. These engineering design elements combined with advanced physics helped enable the compact stellarator to be a viable concept. This paper provides a brief historical overview of the progress in designing stellarator power plants and a perspective on the successful integration of the nuclear activity into the final ARIES-CS configuration.

Plasma Physics and Controlled Fusion, 2001

Compact optimized stellarators offer novel solutions for confining high-β plasmas and developing magnetic confinement fusion. The three-dimensional plasma shape can be designed to enhance the magnetohydrodynamic (MHD) stability without feedback or nearby conducting structures and provide driftorbit confinement similar to tokamaks. These configurations offer the possibility of combining the steady-state low-recirculating power, external control, and disruption resilience of previous stellarators with the low aspect ratio, high β limit, and good confinement of advanced tokamaks. Quasiaxisymmetric equilibria have been developed for the proposed National Compact Stellarator Experiment (NCSX) with average aspect ratio 4-4.4 and average elongation ∼1.8. Even with bootstrap-current consistent profiles, they are passively stable to the ballooning, kink, vertical, Mercier, and neoclassicaltearing modes for β > 4%, without the need for external feedback or conducting walls. The bootstrap current generates only 1/4 of the magnetic rotational transform at β = 4% (the rest is from the coils); thus the equilibrium is much less non-linear and is more controllable than similar advanced tokamaks. The enhanced stability is a result of 'reversed' global shear, the spatial distribution of local shear, and the large fraction of externally generated transform. Transport simulations show adequate fast-ion confinement and thermal neoclassical transport similar to equivalent tokamaks. Modular coils have been designed which reproduce the physics properties, provide good flux surfaces, and allow flexible variation of the plasma shape to control the predicted MHD stability and transport properties.

All Things Ancient Egypt: An Encyclopedia of the Ancient Egyptian World. Volume 1 (ABC-CLIO, Inc)., 2019

The best answer to the Steppe Sons hoax reported in The Economist, is provided by BB Lal. His lecture in 2007 is reproduced below for ready reference. For details of the hoax see: Steppe sons, A new study squelches a treasured theory about Indians’ origins -- The Economist http://bharatkalyan97.blogspot.in/2018/04/steppe-sons-new-study-squelches.html TO REVERT TO THE THEORY OF ‘ARYAN INVASION’ -- BB Lal (2007) Inaugural Address delivered at the 19th International Conference of European Association of South Asian Archaeologists on South Asian Archaeology at University of Bologna, Ravenna, Italy on 2–6 July 2007 Distinguished fellow delegates and other members of the audience, I am most grateful to the organizers of this conference, in particular to the President, Professor Maurizio Tosi, not only for inviting me to participate in this Conference but also for giving me the additional honour of delivering the Inaugural Address. Indeed, I have no words to thank them adequately for their kindness. Perhaps this is the first occasion when a South Asian is being given this privileged treatment by the European Association of South Asian Archaeologists. The conference hall is full of scholars from all parts of the world – from the United States of America on the west to the Land of the Rising Sun, Japan, on the east. All these scholars have contributed in a number of ways to our understanding of the past of South Asia, and I salute them with all the humility that I can muster. However, I hope I will not be misunderstood when I say that some amongst us have not yet been able to shake off the 19th-century biases that have blurred our vision of South Asia’s past. As is well known, it was the renowned German scholar Max Muller who, in the 19th century, attempted for the first time to date the Vedas. Accepting that the Sutra literature was datable to the 6th century BCE, he gave a block-period of 200 years to the preceding three parts of the Vedic literature, namely the Aranyakas, Brahmanas and Vedas. Thus, he arrived at 1200 BCE as the date of the Vedas. However, when his contemporaries, like Goldstucker, Whitney and Wilson, objected to his ad-hocism, he toned down, and finally surrendered by saying (Max Muller 1890, reprint 1979): “Whether the Vedic hymns were composed [in] 1000 or 1500 or 2000 or 3000 BC, no power on earth will ever determine.” But the great pity is that, in spite of such a candid confession by the savant himself, many of his followers continue to swear by his initial dating, viz. 1200 BCE. The ultimate effect of this blind tenacity was that when in the 1920s the great civilization, now known variously as the Harappan, Indus or Indus-Sarasvati Civilization, was discovered in South Asia, and was dated to the 3rd millennium BCE, it was argued that since the Vedas were no earlier than 1200 BCE, the Harappan Civilization could not have been Vedic. Further, since the only other major linguistic group in the region was the Dravidian, it was held that the Harappans were a Dravidian-speaking people. Then came the master stroke. In 1946, my revered guru Mortimer Wheeler (later knighted) discovered a fortification wall at Harappa and on learning that the Aryan god Indra had been referred to as puramdara (destroyer of forts) he readily pronounced his judgment (Wheeler 1947: 82): “On circumstantial evidence Indra [representing the Aryans] stands accused [of destroying the Harappan Civilization].” In further support of his thesis, he cited certain human skeletons at Mohenjo-daro, saying that these were the people massacred by the Aryan invaders. Thus was reached the peak of the ‘Aryan Invasion’ theory. And lo and behold! The very first one to fall in the trap of the ‘Aryan Invasion’ theory was none else but the guru’s disciple himself. With all the enthusiasm inherited from the guru, I started looking for the remains of some culture that may be post-Harappan but anterior to the early historical times. In my exploration of the sites associated with the Mahabharata story I came across the Painted Grey Ware Culture which fitted the bill. It antedated the Northern Black Polished Ware whose beginning went back to the 6th-7th century BCE, and overlay, with a break in between, the Ochre Colour Ware of the early 2nd millennium BCE. In my report on the excavations at Hastinapura and in a few subsequent papers I expressed the view that the Painted Grey Ware Culture represented the early Aryans in India. But the honeymoon was soon to be over. Excavations in the middle Ganga valley threw up in the pre-NBP strata a ceramic industry with the same shapes (viz. bowls and dishes) and painted designs as in the case of the PGW, the only difference being that in the former case the ware had a black or black-and-red surface-colour, which, however, was just the result of a particular method of firing. And even the associated cultural equipment was alike in the two cases. All this similarity opened my eyes and I could no longer sustain the theory of the PGW having been a representative of the early Aryans in India. (The association of this Ware with the Mahabharata story was nevertheless sustainable since that event comes at a later stage in the sequence.) I had no qualms in abandoning my then-favourite theory. But linguists are far ahead of archaeologists in pushing the poor Aryans through the Khyber / Bolan passes into India. In doing so, they would not mind even distorting the original Sanskrit texts. A case in point is that of the well known Professor of Sanskrit at the Harvard University, Professor Witzel. He did not hesitate to mistranslate a part of the Baudhayana Srautasutra (Witzel 1995: 320-21). In 2003 I published a paper in the East and West (Vol. 53, Nos. 1-4), exposing his manipulation. Witzel’s translation of the relevant Sanskrit text was as follows: "Aya went eastwards. His (people) are the Kuru-Pancalas and Kasi Videha. This is the Ayava(migration).(His other people)stayed at home in the west. His people are the Gandhari, Parasu and Aratta. This is the Amavasava (group). Whereas the correct translation is: Ayu migrated eastwards. His (people) are the Kuru-Pancalas and the Kasi-Videhas. This is the Ayava (migration). Amavasu migrated westwards. His (people) are the Ghandhari, Parsu and Aratta. This is the Amavasu (migration). According to the correct translation, there was no movement of the Aryan people from anywhere in the north-west. On the other hand, the evidence indicates that it was from an intermediary point that some of the Aryan tribes went eastwards and other westwards. This would be clear from the map that follows(Fig. 1).

The paper is devoted to the experiences of the 1st Brigade of the Legion who were transferred to the Italian Front in September 1917 after the Oath Crisis. Founded officially in December 1914 under the command of Józef Piłsudski, the 1st Brigade was characterised by its independent nature in relation to the rest of the Austro-Hungarian army as “Polish soldiers, infantry without a Fatherland, fighting alongside another army” and bound closely to the person of their commander. After the 5th of November 1916, when the 1st Brigade refused to pledge allegiance to the Emperors of Germany and Austro-Hungary in July 1917, its officers, citizens of the Kingdom of Poland, were sent to internment camps in Beniaminów, with the non-commissioned offices sent to Szczypiorno. Józef Piłsudski and Kazimierz Sosnkowski were themselves held in Magdeburg whilst legionnaires from Galicia were interned in Huszt, Marmaros-Sziget or forced to join other Austrian army units and sent to the Italian Front in order to fight far from their homeland. The Legionnaires of the 1st Brigade took part in the last German-Austrian offensive in June 1918 (the Battle of the Piave River). The impressions of Piłsudski’s legionnaires is compared with the memoirs of other Polish soldiers from Galicia who had been called up to serve in the Austro-Hungarian army earlier in the war and had seen action on the Italian Front at the end of 1915 and took part in the Fourth and Fifth Battle of the Isonzo in 1916.