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In order to optimize the operational safety and reliability of the upper launcher for the CFETR ECRH system, a design of the launcher based on the remote steering concept is currently being carried out for comparison with the front steering equivalent. This paper presents the remote steering system's conceptual design and simulation analysis. A Square Corrugated Waveguide (SCW) of 65 × 65 mm has been designed with an optimized length of 9.35 m. By changing the relative length of the waveguide, the transmission efficiency of the SCW is optimized within the range of steering angles ±12°. Different error factors are investigated in detail, and corresponding acceptable error ranges are provided. Considering these error factors and ignoring ohmic losses and thermal effects, the relative transmission efficiency of the SCW is estimated to be >98 % within the steering angle range. A matching steering unit for the SCW is designed, which consists of an ellipsoidal focusing mirror and a steerable flat mirror. The detailed design of the steerable mirror motion trajectory is presented. Also, the influence of the possible beam incident errors caused by the steering unit on the transmission efficiency is analyzed in detail.

For the ECRH heating system of the stellarator Wendelstein 7-X, two remote steering antennas are developed and manufactured. The principle of remote steering antennas is based on the imaging characteristics of corrugated rectangular waveguides, which is well understood and can accurately be simulated. Several details, however, require deeper investigation. The antenna needs a miter-bend and a 24 mm gap. The positions of these elements need to be chosen carefully to reduce losses and stray radiation. The antennas are manufactured from copper by electroforming. This allows to integrate all components, including the corrugated inner walls and the cooling channels, in one vacuum-tight piece. This paper reviews the design process of the remote steering antennas for W7-X as well as technological issues and experimental results from test pieces. [ABSTRACT FROM AUTHOR]

The principles and design of 'active' self-propelling particles that can convert energy, move directionally on their own, and perform a certain function is an emerging multidisciplinary research field, with high potential for future technologies. A simple and effective technique is presented for on-demand steering of self-propelling microdiodes that move electroosmotically on water surface, while supplied with energy by an external alternating (AC) field. It is demonstrated how one can control remotely the direction of diode locomotion by electronically modifying the applied AC signal. The swimming diodes change their direction of motion when a wave asymmetry (equivalent to a DC offset) is introduced into the signal. The data analysis shows that the ability to control and reverse the direction of motion is a result of the electrostatic torque between the asymmetrically polarized diodes and the ionic charges redistributed in the vessel. This novel principle of electrical signal-coded steering of active functional devices, such as diodes and microcircuits, can find applications in motile sensors, MEMs, and microrobotics. [ABSTRACT FROM AUTHOR]

Abstract: The design of a remote steering (RS) variant of the electron cyclotron heating (ECH) upper port launcher (UPL) for neo-classical tearing mode (NTM) stabilization in ITER is being finalised. The RS variant is the fall-back option for the reference design, which is a front steering (FS) UPL. This paper presents the changes made in the design of the RS UPL with respect to the previous baseline (the October 2005 baseline) design. The changes are motivated by a demand to improve the reliability of the launching system by solving a number of pressing issues. To accomplish this, a reduction in the steering range of the launcher was proposed. This reduction yields more tolerable head loads on the focusing elements for a given performance. Modifications of the launcher layout allow for an increase of the toroidal injection angle, which improves the NTM stabilization efficiency. A mode converter can reduce the stray radiation in the vicinity of the steering mechanism down to tolerable levels. Abandoning the concept of the mini-duct leads to a reduction of stray radiation concerns and allows for the implementation of improved alignment facilities of the individual steerable mirror units. The work shows that a launcher based on the RS principle is feasible. This launcher can be made reliable, flexible and easily accessible for maintenance purposes accepting the consequent limitations in the achievable steering range inside the ITER plasma. [Copyright &y& Elsevier]

This paper is devoted to the theoretical analysis of Talbot effects in a curved square waveguide. A remote steering antenna as an important application of Talbot effects is considered. It is shown that the wavebeam repetition is considerably spoiled by the curvature even for bending angles about 5° if the steering plane coincides with the bending plane. However, high-efficient repetition exists at certain launching angles. If the wavebeam steering plane is perpendicular to the waveguide bending plane, high-efficient repetition takes place in a broad band of launching angles in the waveguide of the optimized rectangular cross-section. [ABSTRACT FROM AUTHOR]

Abstract: In order to exploit the capability of electron cyclotron waves (ECW) for localized heating and current drive over a large range of plasma radii in ITER, the electron cyclotron heating (ECH) and current drive (CD) upper port launcher needs a beam steering capability. In this paper the remote steering (RS) option is described as it is being studied by a number of European institutes. For the remote-steering approach a number of critical design issues were identified by the EFDA and ITER-IT teams. All technical design issues could be solved but the performance of the system, as far as stabilization of neoclasical tearing modes (NTMs) is concerned was not sufficient for all the required ITER plasma scenarios. In order to overcome this, new design efforts are ongoing in order to improve the performance of the RS setup at the relevant NTM positions. An increase of the square wave-guide length to around 9m is foreseen to enhance the current-drive capability to the minimum levels that are needed to stabilize the 3/2 and 2/1 NTM modes in nearly all ITER scenarios. [Copyright &y& Elsevier]

An interesting protocol for classical teleportation of an unknown classical state was recently suggested by Cohen, and by Gour and Meyer. In that protocol, Bob can sample from a probability distribution $\mathcal{P}$ that is given to Alice, even if Alice has absolutely no knowledge about $\mathcal{P}$. Pursuing a similar line of thought, we suggest here a limited form of non-locality — "classical non-locality." Our non-locality is the (somewhat limited) classical analogue of the Hughston–Jozsa–Wootters (HJW) quantum non-locality. The HJW non-locality (also known as "quantum remote steering") tells us how, for a given density matrix ρ, Alice can generate any ρ-ensemble on the North Star. This is done using surprisingly few resources — one shared entangled state (prepared in advance), one generalized quantum measurement, and no communication. Similarly, our classical non-locality (which we call "classical remote steering") presents how, for a given probability distribution $\mathcal{P}$, Alice can generate any $\mathcal{P}$-ensemble on the North Star, using only one correlated state (prepared in advance), one (generalized) classical measurement, and no communication. It is important to clarify that while the classical teleportation and the classical non-locality protocols are probably rather insignificant from a classical information processing point of view, they significantly contribute to our understanding of what exactly is quantum in their well established and highly famous quantum analogues. [ABSTRACT FROM AUTHOR]

Abstract: An ECRH (electron cyclotron resonance heating) launching system (Fig. 1) for the ITER upper ports is being designed. The aim of the system is to inject electron cyclotron waves (ECW) in the ITER plasma in order to stabilize neoclassical tearing modes (NTM). Each upper-port launcher consists of eight mm-wave beam lines capable of transmitting high power up to 2MW at 170GHz into the plasma. In order to exploit the capability of ECW for localized heating and current drive over a range of plasma radii in ITER, the ECH&CD upper port launching system must have a beam steering capability. To avoid movable mirrors at the plasma-facing end of the launcher, the concept of remote mm-wave beam steering (RS) is used, having a square corrugated waveguide (SCW) located inside the port-plug, which is primary (torus) vacuum. The steerable mirror units are placed outside of the first confinement boundary of the vacuum vessel. FOM is developing a full-scale mm-wave launching system mock-up. The mock-up consists of a launching system in a set of vacuum vessels, in order to provide the most ITER-like operation conditions. The mock-up will first be used at the FOM institute in The Netherlands to test the launching system at low power. In 2005, tests will be done in Karlsruhe at high power and short pulses. The mock-up will be shipped again to The Netherlands after the tests in Karlsruhe to prepare it for the Lausanne 2MW, cw tests. [Copyright &y& Elsevier]