First evidence of nuclear polarization effects in a laser-induced 3 ⁣^3\mkern-1muHe fusion plasma

Polarized fusion has long ago be proposed as a method to strongly increase the efficiency of fusion reactors. However, the required nuclear spin-polarization conservation in fusion plasmas has never been proven experimentally. Here we report on first experimental data suggesting an increased ion flux from a polarized $^3\mkern-1mu$He target heated by a PW laser pulse as well as evidence for an almost complete persistence of their nuclear-polarization after acceleration to MeV energies. These findings also validate the concept of using pre-polarized targets for plasma acceleration of polarized beams

Resources in Economic Geography: From Substantive Concepts Towards a Relational Perspective

The version of record [Bathelt, H., & Gluckler, J. (2005). Resources in economic geography: From substantive concepts towards a relational perspective. Environment and Planning A, 37(9), 1545-1563.] is available online at: http://epn.sagepub.com/content/37/9/1545 [doi: 10.1068/a37109]Resources are crucial for the technological and economic development of firms in spatial perspective. In this paper we contrast two ways of conceptualizing resources, and argue that a conventional, substantive understanding implies a number of shortcomings which can be overcome through the application of a relational conception of resources. In examining four types of resources—material resources, knowledge, power, and social capital—our argument is that resources are constituted in a relational way in two aspects. First, resources are relational in that their generation, interpretation, and use are contingent. This depends on the particular institutional structures and social relations, as well as on the knowledge contexts and mental models of the agents involved. Second, some types of resources, such as power and social capital, are also relational because they cannot be possessed or controlled by individual agents. They are built and mobilized through day-to-day social practices. Individuals or groups of agents may appropriate the returns, but not the resources themselves. We conclude that a relational concept reflects the contextual and interactive nature of the selection, use, and formation of resources. This offers new insights into the explanation of heterogeneity in firm strategies and trajectories, as well as regional differences in the development of localized industry configurations, such as clusters

Institutional Change in Economic Geography

The version of record [Bathelt, H., & Glückler, J. (2014). Institutional change in economic geography. Progress in Human Geography, 38(3), 340- 363.] is available online at: http://phg.sagepub.com/content/38/3/340 [doi: 10.1177/0309132513507823]This paper develops a rigorous concept of institutions to investigate the interrelationships between institutional and economic change from the perspective of economic geography. We view institutions neither as behavioural regularities nor as organizations or rules, but conceive institutions as stabilizations of mutual expectations and correlated interaction. The paper discusses how economic interaction in space is shaped by existing institutions, how this leads to economic decisions and new rounds of action, and how their intended and unintended consequences impact or enact new/existing institutions. The paper explores three modes of institutional change – hysteresis, emergent change, and institutional entrepreneurship

Toward a relational economic geography

This is a pre-copyedited, author-produced PDF of an article accepted for publication in Journal of Economic Geography following peer review. The version of record [Bathelt, H., & Glückler, J. (2003). Toward a relational economic geography. Journal of Economic Geography, 3(2), 117- 144.] is available online at: http://joeg.oxfordjournals.org/content/3/2/117 [doi: 10.1093/jeg/3.2.117].In this paper, we argue that a paradigmatic shift is occurring in economic geography toward a relational economic geography. This rests on three propositions. First, from a structural perspective economic actors are situated in contexts of social and institutional relations. Second, in dynamic perspective economic processes are path‐dependent, constrained by history. Third, economic processes are contingent in that the agents' strategies and actions are open‐ended. Drawing on Storper's holy trinity, we define four ions as the basis for analysis in economic geography: organization, evolution, innovation, and interaction. Therein, we employ a particular spatial perspective of economic processes using a geographical lens

A Permanent-Magnet Array to Maintain 3He Gas Polarization Inside a Glass Vessel for Applications in High-Energy Laser Physics

We designed and tested an array of permanent magnets (PMA) consisting of two rings with a Halbach-type magnetization pattern, which are stacked at an optimum distance such that its field homogeneity is sufficiently high to maintain the nuclear polarization of 3He gas for future laser experiments. The design included the magnetic layout, the selection of appropriate magnets, and the calculation of the expected relaxation time for the polarized gas. After assembly, we measured the magnetic field in the center region of the PMA. We transferred polarized gas samples from the magnetized transport box into the PMA and determined the relaxation time with four magnetic field sensors in a gradiometric arrangement, detecting the decay of the stray field of the polarized gas on the order of 100 nT in a background field of 1.3 mT. The extracted polarization lifetime of about 21 h is sufficient for the planned experiments at high-power laser facilities

Developments for the Injection Kicker Vacuum System of the HESR at FAIR

The Research Center Jülich has taken the leadership of a consortium being responsible for the design and manufacturing of the High-Energy Storage Ring (HESR) going to be part of FAIR. The HESR is designed both for antiprotons and for heavy ion experiments. The injection kicker system of the HESR is located directly behind the septum and consists of two pumping crosses for pumps and measurement devices as well as two vacuum tanks housing the four ferrite magnets which will be operated with 40 kV, 4kA. As well as the magnets, the adjustments frames and the electrical feedthroughs will be installed inside the tanks. Due to the large surface of the magnets the injection kicker system will be very sensitive with regard to the achievable vacuum quality that is expected to be in the order of 10⁻¹¹ mbar or better. Thus the vacuum system is designed to heat up to 250°C. In order to investigate the achievable end pressure and to develop the heating system a test facility was constructed. The actual vacuum layout of the injection kicker system as well as the experimental test results will be presented and in similar the layout of the control system of the test facility will be described

Polarimetry for 3He Ion Beams from Laser–Plasma Interactions

We present a compact polarimeter for 3He ions with special emphasis on the analysis of short-pulsed beams accelerated during laser–plasma interactions. We discuss the specific boundary conditions for the polarimeter, such as the properties of laser-driven ion beams, the selection of the polarization-sensitive reaction in the polarimeter, the representation of the analyzing-power contour map, the choice of the detector material used for particle identification, as well as the production procedure of the required deuterated foil-targets. The assembled polarimeter has been tested using a tandem accelerator delivering unpolarized 3He ion beams, demonstrating good performance in the few-MeV range. The statistical accuracy and the deduced figure-of-merit of the polarimetry are discussed, including the count-rate requirement and the lower limit of accuracy for beam-polarization measurements at a laser-based ion source

A High-Density Polarized 3He Gas–Jet Target for Laser–Plasma Applications

A laser-driven spin-polarized 3He2+-beam source for nuclear–physics experiments and for the investigation of polarized nuclear fusion demands a high-density polarized 3He gas-jet target. Such a target requires a magnetic system providing a permanent homogeneous holding field for the nuclear spins plus a set of coils for adjusting the orientation of the polarization. Starting from a transport vessel at a maximum pressure of 3 bar, the helium gas is compressed for a short time and can be injected into a laser–interaction chamber through a non-magnetic opening valve and nozzle, thus forming jets with densities of about a few 1019 cm−3 and widths of about 1 mm. The target comprises a 3D adjustment system for precise positioning of the jet relative to the laser focus. An auxiliary gas system provides remote target operation and flushing of the gas lines with Ar gas, which helps to reduce polarization losses. The design of the target, its operation procedures and first experimental results are presented