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Effects of edge safety factor on the toroidal flow velocity of the STOR-M plasma.2015 February 1900 (has links)
The effect of changing edge safety factor on the toroidal flow of the STOR-M plasma has been investigated during the application of both resonant magnetic perturbation (RMP) and compact torus injection (CTI). The edge safety factor was varied by varying the plasma current while keeping the toroidal field constant. A Czyner-Turner spectrometer was used to collect the spectral data from which the velocity of specific impurity ions was diagnosed. Time resolved velocity measurements were inferred from the Doppler wavelength shift of the emission lines. Impurity emission lines at different ionization stages are located at different radial locations within the STOR-M plasma. Properties of these impurity ions are assumed to be closely related the hydrogen ion (main working gas) due to the strong interaction among the ion species.
Changing the edge safety factor has a similar effect on the toroidal flow of STOR-M plasma during discharges with both RMP and CTI. A velocity shear was discovered for different impurity ions. The toroidal flow is enhanced for edge ions while a reversal of flow is observed for core ions. As the edge safety factor reduces, the emission location for the core ions is located with q=2 surface and RMP has a significant impact on their toroidal flow velocity. It was also observed that CT injection has a significant effect on the toroidal velocity of the core ions compared to that of the edge ions. In addition, high plasma current (low safety factor) induced large change in the toroidal flow velocity of the STOR-M plasma.
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Plasma Flow Velocity Measurements Using A Gundestrup Probe In The STOR-M TokamakSt. Germaine, Geoffrey Martin Reginald 22 August 2006
The profile of the poloidal velocity in the edge region of tokamak plasmas has been identified as playing a major role in the confinement of particles and energy. It has been suggested that a strongly sheared poloidal flow can reduce particle and energy losses by the stabilization of unstable modes and decorrelation of turbulence the edge region of the plasma. A Gundestrup probe, a Mach probe array, is used to measure both the parallel and perpendicular flow velocities in the Saskatchewan Torus-Modified (STOR-M) tokamak during several discharge conditions. It is observed that during Ohmic discharges there is no velocity shear and the direction of the parallel flow is independent of the direction of the toroidal magnetic field. During H-mode induced by a turbulent heating current pulse, a region of strong velocity shear develops in the plasma edge and an edge transport barrier develops. This results in a short period of improved particle and energy confinement with reduced fluctuation amplitudes. During electrode biasing experiments, a stainless steel biasing electrode is inserted into the plasma up to r = 82 mm and biased to +500 V relative to the vacuum chamber. It is observed that the particle confinement improves during the biasing phase while the energy confinement is degraded. A region of weak shear in the poloidal flow is observed in the plasma scrapeoff layer (SOL). The results from STOR-M are compared with results from data taken in the Czech Academy of Sciences Torus (CASTOR) tokamak during both Ohmic discharges and discharges with electrode biasing.
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Plasma flow velocity measurements with a Gundestrup probe in the STOR-M tokamakSt. Germaine, Geoffrey Martin Reginald 23 August 2006
The profile of the poloidal velocity in the edge region of tokamak plasmas has been identified as playing a major role in the confinement of particles and energy. It has been suggested that a strongly sheared poloidal flow can reduce particle and energy losses by the stabilization of unstable modes and decorrelation of turbulence the edge region of the plasma. A Gundestrup probe, a Mach probe array, is used to measure both the parallel and perpendicular flow velocities in the Saskatchewan Torus-Modified (STOR-M) tokamak during several discharge conditions. It is observed that during Ohmic discharges there is no velocity shear and the direction of the parallel flow is independent of the direction of the toroidal magnetic field. During H-mode induced by a turbulent heating current pulse, a region of strong velocity shear develops in the plasma edge and an edge transport barrier develops. This results in a short period of improved particle and energy confinement with reduced fluctuation amplitudes. During electrode biasing experiments, a stainless steel biasing electrode is inserted into the plasma up to r = 82 mm and biased to +500 V relative to the vacuum chamber. It is observed that the particle confinement improves during the biasing phase while the energy confinement is degraded. A region of weak shear in the poloidal flow is observed in the plasma scrapeoff layer (SOL). The results from STOR-M are compared with results from data taken in the Czech Academy of Sciences Torus (CASTOR) tokamak during both Ohmic discharges and discharges with electrode biasing.
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Plasma flow velocity measurements with a Gundestrup probe in the STOR-M tokamakSt. Germaine, Geoffrey Martin Reginald 23 August 2006 (has links)
The profile of the poloidal velocity in the edge region of tokamak plasmas has been identified as playing a major role in the confinement of particles and energy. It has been suggested that a strongly sheared poloidal flow can reduce particle and energy losses by the stabilization of unstable modes and decorrelation of turbulence the edge region of the plasma. A Gundestrup probe, a Mach probe array, is used to measure both the parallel and perpendicular flow velocities in the Saskatchewan Torus-Modified (STOR-M) tokamak during several discharge conditions. It is observed that during Ohmic discharges there is no velocity shear and the direction of the parallel flow is independent of the direction of the toroidal magnetic field. During H-mode induced by a turbulent heating current pulse, a region of strong velocity shear develops in the plasma edge and an edge transport barrier develops. This results in a short period of improved particle and energy confinement with reduced fluctuation amplitudes. During electrode biasing experiments, a stainless steel biasing electrode is inserted into the plasma up to r = 82 mm and biased to +500 V relative to the vacuum chamber. It is observed that the particle confinement improves during the biasing phase while the energy confinement is degraded. A region of weak shear in the poloidal flow is observed in the plasma scrapeoff layer (SOL). The results from STOR-M are compared with results from data taken in the Czech Academy of Sciences Torus (CASTOR) tokamak during both Ohmic discharges and discharges with electrode biasing.
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<b>EXPLORING REGIME MAPPING IN TOROIDAL FLUID BED GRANULATION: TOWARDS OPTIMIZED PROCESS CONTROL</b>Line Koleilat (20376486) 10 December 2024 (has links)
<p dir="ltr">Flow patterns in a toroidal-fluidized bed granulator were analyzed using the effects of wall friction on the bed pressure drop. Toroidal flows were generated by directionally inclined jets from a radially-slotted distributor plate. The relatively small open area of the slotted distributor provides significant jet velocities, inducing toroidal flow even at relatively low superficial airflows. In this aspect, the process is of interest to fluidized bed granulation wherein the toroidal flow can assist spray flux without excessive elutriation. The current dissertation explores the effect of toroidal multiphase flow on wall friction and pressure drop. Relevant process parameters include particle size, airflow, temperature, and bed inventory. Particle size growth is especially important in fluidized bed granulation; airflow and temperature parameters must balance with the binder spray enthalpy; and the bed inventory is relevant to capacity and throughput analyses. An empirical process model was developed to guide fluidized bed granulation with a consistent pressure-drop balance across the distributor plate and product bed during the granulation process.</p><p dir="ltr">Fluidized bed granulation integrates several process transformations into a single unit operation. Transformations include powder fluidization, atomization of binder solution and wetting of the fluidized powder, growth and consolidation of granules, drying, and discharge of the fluidized product. The balance of the binder addition and drying rates is used in combination with fluidization (i.e., flow field) parameters to control the process. Balanced control of fluidization can be challenging in the context of micronized powders, prone to elutriation, for example as required in some pharmaceutical formulations. This manuscript explores the effects of thermodynamic and flow field parameters on the size and shape distributions of a challenging pharmaceutical formulation. Pre-wetting the powder mixture prior to fluidization effectively reduces elutriation, stabilizes the fluidization process, and results in narrower granule size distributions. Optimizing blowback pressure can further stabilize the process. These strategies contribute to improved control of fluidized bed granulation, particularly for challenging pharmaceutical formulations, enhancing both product quality and process efficiency.</p><p dir="ltr">A regime map for a challenging pharmaceutical formulation was developed to link operational parameters to granule characteristics, establishing a stable processing space that connects moisture gain with particle size and shape distributions and uniformity. This comprehensive framework supports scale-up and reliable application of fluid bed granulation in pharmaceutical and related industries, contributing to improved process efficiency and product quality. The findings presented here advance the scientific understanding of toroidal fluid bed granulation and offer practical and actionable strategies for controlling this process.</p>
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