Particle and recycling control in translation, confinement, and sustainment upgrade

Abstract

Previous work in the translation, confinement, and sustainment upgrade ͑TCSU͒ device ͓H. Y. Guo et al., Phys. Plasmas 15, 056101 ͑2008͔͒ demonstrated improved plasma parameters; higher temperature, higher poloidal magnetic field, increased current drive, and increased energy confinement, for rotating magnetic field ͑RMF͒ driven field reversed configurations ͑FRC͒ relative to the earlier TCS device. This was accomplished by improving vacuum conditions and using moderate wall heating ͑ϳ100°C͒ and glow discharge cleaning for wall conditioning. Two new wall conditioning techniques, siliconization and titanium gettering, have been employed to further reduce impurities and control recycling. Both techniques reduced oxygen line radiation by an order of magnitude, and total radiated power by 50%, but led to little change in overall FRC performance, reinforcing the earlier conclusion that TCSU FRCs are not radiation dominated. Titanium gettering substantially reduced deuterium recycling, requiring a new method of fueling to be developed. This is the first time a FRC has been operated without using wall recycling as the primary method of fueling. The low-recycling FRCs, maintained by enhanced puff fueling, performed similarly to standard recycling fueled FRCs in terms of a key current drive parameter B e / B , the ratio of maximum sustained poloidal field to applied RMF field, but better density control allowed for higher temperatures.

Highly selective oxidation of methane to methanol at ambient conditions by titanium dioxide-supported iron species

“…The main peaks located at ca.710 eV and 725 eV are associated with the Fe 2p 3/2 and Fe 2p 1/2, respectively. [49][50][51] They can be further fitted with six peaks as shown in Figure 3b. Two peaks located at 710 eV and 724 eV are associated with an Fe(III) oxidation state.…”

“…Two peaks located at 710 eV and 724 eV are associated with an Fe(III) oxidation state. [49][50][51] The satellite peaks at 719 eV and 728 eV are also the fingerprint of an Fe(III) oxidation state. [49][50][51] The additional peaks at 714 eV and 726 eV are related to the effects of hydroxide groups.…”

“…[49][50][51] The satellite peaks at 719 eV and 728 eV are also the fingerprint of an Fe(III) oxidation state. [49][50][51] The additional peaks at 714 eV and 726 eV are related to the effects of hydroxide groups. 49,51 The chemical states of the iron species were further confirmed by X-ray near edge structure (XANES) spectroscopies.…”

Extended magnetohydrodynamic simulations of field reversed configuration formation and sustainment with rotating magnetic field current drive

“…A large isotropic thermal conductivity is assumed and adjusted to yield a temperature in the 50-70 eV range ͑total temperature T t = T e + T i is in the 120-140 eV range͒, as observed in the TCSU experiment. 18,20 On the radial boundary the n = 0 component of B is set to 0 corresponding to no net axial current. The n = 0 component of B r is held at its initial value, and the n = 0 component of E = 0, corresponding to no change in the value of the poloidal flux function along the boundary.…”

Measurements accounting for the impediment of ion spin-up in rotating magnetic field driven field reversed configurations

“…Wall conditioning and improved vacuum hygiene have led to a lower neutral density background. 8 Further, internal rings have been installed that force the plasma away from the wall; this may reduce the viscous drag on the ions. The purpose of this paper is to calculate a torque balance in the TCSU device using an improved RMF torque model as well as diagnostics to determine counter torques due to particle loss, ion-neutral interactions, viscosity, and end-shorting.…”