Analytic Criteria for Power Exhaust in Divertors due to Impurity Radiation

Present divertor concepts for next step experiments such ITER and TPX rely upon impurity and hydrogen radiation to transfer the energy from the edge plasma to the main chamber and divertor chamber walls. The efficiency of these processes depends strongly on the heat flux, the impurity species, and the connection length. Using a database for impurity radiation rates constructed from the ADPAK code package, we have developed criteria for the required impurity fraction, impurity species, connection length and electron temperature and density at the mid-plane. Consistent with previous work, we find that the impurity radiation from coronal equilibrium rates is, in general, not adequate to exhaust the highest expected heating powers in present and future experiments. As suggested by others, we examine the effects of enhancing the radiation rates with charge exchange recombination and impurity recycling, and develop criteria for the minimum neutral fraction and impurity recycling rate that is required to exhaust a specified power. We also use this criteria to find the optimum impurity for divertor power exhaust.Comment: Preprint for the 11th PSI meeting, Adobe pdf with 14 figures, 15 page

Axiomatic Information Thermodynamics

We present an axiomatic framework for thermodynamics that incorporates information as a fundamental concept. The axioms describe both ordinary thermodynamic processes and those in which information is acquired, used and erased, as in the operation of Maxwell's demon. This system, like previous axiomatic systems for thermodynamics, supports the construction of conserved quantities and an entropy function governing state changes. Here, however, the entropy exhibits both information and thermodynamic aspects. Although our axioms are not based upon probabilistic concepts, a natural and highly useful concept of probability emerges from the entropy function itself. Our abstract system has many models, including both classical and quantum examples.Comment: 52 pages, 5 figures. Revised 28 Mar 201

Court’s Choice of Law Ruling Undermines Washington Community Property Law: A Critique of Shanghai Commercial Bank v. Chang

This Article deals with the issues that arise when Washington courts face the following scenario. One spouse enters into a contract without the joinder (and perhaps without the knowledge) of the other spouse. Both spouses are domiciled in Washington. The contract has contacts with one or more jurisdictions other than Washington and is generally governed as to validity and interpretation by the law of another jurisdiction. The contracting spouse defaults and the other party to the contract obtains a judgment on the contract. The court confronts a question about the property to which the plaintiff will have recourse to collect the judgment. This Article will briefly describe the basics of Washington’s community property laws as they relate to contract obligations incurred by one spouse without the joinder of the other. It will then survey Washington’s choice of law rules generally and its earlier cases dealing with the choice of law for the property recourse issue. Finally, it will discuss and critique the Shanghai Commercial case in more detail. It respectfully concludes that Shanghai Commercial was wrongly decided both as a policy matter and in its application of prior Washington law and that the courts of Arizona, another community property state, have taken a better approach to the property recourse issue

Radiation Rates for Low Z Impurities in Edge Plasmas

The role of impurity radiation in the reduction of heat loads on divertor plates in present experiments such as DIII-D, JET, JT-60, ASDEX, and Alcator C-Mod, and in planned experiments such as ITER and TPX places a new degree of importance on the accuracy of impurity radiation emission rates for electron temperatures below 250 eV for ITER and below 150 eV for present experiments. We have calculated the radiated power loss using a collisional radiative model for Be, B, C, Ne and Ar using a multiple configuration interaction model which includes density dependent effects, as well as a very detailed treatment of the energy levels and meta-stable levels. The "collisional radiative" effects are very important for Be at temperatures below 10 eV. The same effects are present for higher Z impurities, but not as strongly. For some of the lower Z elements, the new rates are about a factor of two lower than those from a widely used, simpler average-ion package (ADPAK) developed for high Z ions and for higher temperatures. Following the approach of Lengyel for the case where electron heat conduction is the dominant mechanism for heat transport along field lines, our analysis indicates that significant enhancements of the radiation losses above collisional radiative model rates due to such effects as rapid recycling and charge exchange recombination will be necessary for impurity radiation to reduce the peak heat loads on divertor plates for high heat flux experiments such as ITER.Comment: Preprint for the 11th PSI meeting, gzipped postscript with 11 figures, 14 page

High temperature static strain gage alloy development program

The literature, applicable theory and finally an experimental program were used to identify new candidate alloy systems for use as the electrical resistance elements in static strain gages up to 1250K. The program goals were 50 hours of use in the environment of a test stand gas turbine engine with measurement accuracies equal to or better than 10 percent of full scale for strains up to + or - 2000 microstrain. As part of this effort, a computerized electrical resistance measurement system was constructed for use at temperatures between 300K and 1250K and heating and cooling rates of 250K/min and 10K/min. The two best alloys were an iron-chromium-aluminum alloy and a palladium base alloy. Although significant progress was made, it was concluded that a considerable additional effort would be needed to fully optimize and evaluate these candidate systems

On page-based optimistic process checkpointing

Persistent object systems must provide some form of checkpointing to ensure that changes to persistent data are secured on non-volatile storage. When processes share or exchange modified data, mechanisms must be provided to ensure that they may be consistently checkpointed. This may be performed eagerly by synchronously checkpointing all dependent data. Alternatively, optimistic techniques may be used where processes are individually checkpointed and globally consistent states are found asynchronously. This paper examines two eager checkpointing techniques and describes a new optimistic technique. The technique is applicable in systems such as SASOS, where the notion of process and address space are decoupled.Othe

Calculations of Energy Losses due to Atomic Processes in Tokamaks with Applications to the ITER Divertor

Reduction of the peak heat loads on the plasma facing components is essential for the success of the next generation of high fusion power tokamaks such as the International Thermonuclear Experimental Reactor (ITER) 1 . Many present concepts for accomplishing this involve the use of atomic processes to transfer the heat from the plasma to the main chamber and divertor chamber walls and much of the experimental and theoretical physics research in the fusion program is directed toward this issue. The results of these experiments and calculations are the result of a complex interplay of many processes. In order to identify the key features of these experiments and calculations and the relative role of the primary atomic processes, simple quasi-analytic models and the latest atomic physics rate coefficients and cross sections have been used to assess the relative roles of central radiation losses through bremsstrahlung, impurity radiation losses from the plasma edge, charge exchange and hydrogen radiation losses from the scrape-off layer and divertor plasma and impurity radiation losses from the divertor plasma. This anaysis indicates that bremsstrahlung from the plasma center and impurity radiation from the plasma edge and divertor plasma can each play a significant role in reducing the power to the divertor plates, and identifies many of the factors which determine the relative role of each process. For instance, for radiation losses in the divertor to be large enough to radiate the power in the divertor for high power experiments, a neutral fraction of 10-3 to 10-2 and an impurity recycling rate of netrecycle of ~ 10^16 s m^-3 will be required in the divertor.Comment: Preprint for the 1994 APSDPP meeting, uuencoded and gzipped postscript with 22 figures, 40 pages

Towards the production of radiotherapy treatment shells on 3D printers using data derived from DICOM CT and MRI: preclinical feasibility studies

Background: Immobilisation for patients undergoing brain or head and neck radiotherapy is achieved using perspex or thermoplastic devices that require direct moulding to patient anatomy. The mould room visit can be distressing for patients and the shells do not always fit perfectly. In addition the mould room process can be time consuming. With recent developments in three-dimensional (3D) printing technologies comes the potential to generate a treatment shell directly from a computer model of a patient. Typically, a patient requiring radiotherapy treatment will have had a computed tomography (CT) scan and if a computer model of a shell could be obtained directly from the CT data it would reduce patient distress, reduce visits, obtain a close fitting shell and possibly enable the patient to start their radiotherapy treatment more quickly. Purpose: This paper focuses on the first stage of generating the front part of the shell and investigates the dosimetric properties of the materials to show the feasibility of 3D printer materials for the production of a radiotherapy treatment shell. Materials and methods: Computer algorithms are used to segment the surface of the patient’s head from CT and MRI datasets. After segmentation approaches are used to construct a 3D model suitable for printing on a 3D printer. To ensure that 3D printing is feasible the properties of a set of 3D printing materials are tested. Conclusions: The majority of the possible candidate 3D printing materials tested result in very similar attenuation of a therapeutic radiotherapy beam as the Orfit soft-drape masks currently in use in many UK radiotherapy centres. The costs involved in 3D printing are reducing and the applications to medicine are becoming more widely adopted. In this paper we show that 3D printing of bespoke radiotherapy masks is feasible and warrants further investigation

Biomechanical differences between cases with chronic exertional compartment syndrome and asymptomatic controls during walking and marching gait

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.Chronic exertional compartment syndrome is a significant problem in military populations that may be caused by specific military activities. This study aimed to investigate the kinematic and kinetic differences in military cases with chronic exertional compartment syndrome and asymptomatic controls. 20 males with symptoms of chronic exertional compartment syndrome of the anterior compartment and 20 asymptomatic controls were studied. Three-dimensional lower limb kinematics and kinetics were compared during walking and marching. Cases were significantly shorter in stature and took a relatively longer stride in relation to leg length than controls. All kinematic differences identified were at the ankle. Cases demonstrated increased ankle plantarflexion from mid-stance to toe-off. Cases also demonstrated less ankle inversion at the end of stance and early swing phases. Lower ankle inversion moments were observed during mid-stance. The anthropometric and biomechanical differences demonstrated provide a plausible mechanism for the development of chronic exertional compartment syndrome in this population. The shorter stature in combination with the relatively longer stride length observed in cases may result in an increased demand on the anterior compartment musculature during ambulation. The results of this study, together with clinical insights and the literature suggest that the suppression of the walk-to-run stimulus during group marches may play a significant role in the development of chronic exertional compartment syndrome within a military population. The differences in joint angles and moments also suggest an impairment of the muscular control of ankle joint function, such as a reduced effectiveness of tibialis anterior. It is unclear whether this is a cause or consequence of chronic exertional compartment syndrome.This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors