Pellet ablation and temperature profile measurements in TFTR

Conference · Fri Jan 01 00:00:00 EST 1988

OSTI ID:6439538

Owens, D K; Schmidt, G L; Cavallo, A; Grek, B; Hulse, R; Johnson, D; Mansfield, D; McNeill, D; Park, H; Taylor, G

Single and multiple deuterium pellets have been injected into a variety of TFTR plasmas, including ohmically heated plasmas with wide range of electron temperatures, neutral beam heated plasmas at several NBI powers and high T/sub e/, post NBI plasmas. Pellet penetration into these plasmas was determined by measuring the pellet speed and duration of the H/sub ..cap alpha..//D/sub ..cap alpha../ light emission during pellet ablation in the plasma. These penetration measurements are compared to the predicted penetration computed using the ablation model developed by Oak Ridge National Laboratory. The plasma density profiles before and after pellet injection are used to estimate the number of particles deposited in the plasma. The plasma particle increase compared to the estimated number of atoms in the pellet yields a measure of the fueling efficiency of pellets in TFTR. The ablation cloud parameters are discussed based on polychromater measurements of the H/sub ..cap alpha..//D/sub ..cap alpha../ line emission from the neutral cloud surrounding the pellet. The electron temperature profile evolution after pellet injection is examined for the case of multiple pellet injection into an ohmically heated plasma. The ORNL pellet ablation code was used to compare measured pellet penetration depths with a theoretical model. The measured input parameters to the model are the electron density and temperature profiles, the neutral beam heating profile, the neutral density profile, the pellet size, pellet speed and pellet composition. The free parameter in the model is the thickness of the neutral cloud surrounding the pellet. This parameter is adjusted to arrive at a reasonable agreement between measured and calculated pellet penetration depths. The output of the model which is directly comparable to experiment is the calculated ablation rate. It is assumed that the broad-band H/sub ..cap alpha..//D/sub ..cap alpha../ emission is proportional to the ablation rate.

• Research Organization: Oak Ridge National Lab., TN (USA)
• DOE Contract Number: AC05-84OR21400; AC02-76CH03073
• OSTI ID: 6439538
• Report Number(s): CONF-8810231-8; ON: DE89008924
• Conference Information: IAEA technical committee meeting on pellet injection and toroidal confinement, Gut Ising, F.R. Germany, 24 Oct 1988
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700102* -- Fusion Energy-- Plasma Research-- Diagnostics
700205 -- Fusion Power Plant Technology-- Fuel
Heating
& Injection Systems
ABLATION
DEUTERIUM
ELECTRIC HEATING
ELECTRON DENSITY
ELECTRON TEMPERATURE
FUEL PELLETS
HEATING
HYDROGEN ISOTOPES
ISOTOPES
JOULE HEATING
LIGHT NUCLEI
NUCLEI
ODD-ODD NUCLEI
PELLET INJECTION
PELLETS
PLASMA DIAGNOSTICS
PLASMA HEATING
RESISTANCE HEATING
STABLE ISOTOPES
TEMPERATURE DISTRIBUTION
TEMPERATURE MEASUREMENT
TFTR TOKAMAK
THERMONUCLEAR REACTORS
TOKAMAK TYPE REACTORS