ATF edge plasma turbulence studies using a fast reciprocating Langmuir probe
- Oak Ridge National Lab., TN (USA)
- Texas Univ., Austin, TX (USA). Fusion Research Center
Electrostatic turbulence on the edge of the Advanced Toroidal Facility (ATF) torsatron is investigated experimentally with a fast reciprocating Langmuir probe (FRLP) array. Initial measurements of plasma electron density n{sub e} and temperature T{sub e} and fluctuations in density ({tilde n}{sub e}) and plasma floating potential ({tilde {phi}}{sub f}) are made in electron cyclotron heated plasmas at 1 T. At the last closed flux surface (LCFS, r{radical}a {approximately} 1), T{sub e} {approx} 20--40 eV and n{sub e} {approx} 10{sup 12} cm{sup {minus}3} for a line-averaged electron density {bar n}{sub e} = (3--6) {times} 10{sup 12} cm{sup {minus}3}. Relative fluctuation levels, as the FRLP is moved into core plasma where T{sub e} > 20 eV, are {tilde n}{sub e}/n{sub e} {approx} 5% and e{tilde {phi}}{sub f}/T{sub e} {approx} 2{tilde n}{sub e}/n{sub e} about 2 cm inside the LCFS. The observed fluctuation spectra are broadband (40--300 kHz) with {bar k}{rho}{sub s} {le} 0.1, where {bar k} is the wavenumber of the fluctuations and {rho}{sub s} is the ion Larmor radius at the sound speed. The propagation direction of the fluctuations reverses to the electron diamagnetic direction around r{radical}a < 1. The phase velocity and the electron drift velocity are comparable (v{sub ph} {approximately} v{sub de}). The fluctuation-induced particle flux is comparable to fluxes estimated from the particle balance using the H{sub {alpha}} spectroscopic measurements. Many of the features seen in these experiments resemble the features of ohmically heated plasmas in the Texas Experimental Tokamak (TEXT). 18 refs., 10 figs.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (USA)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 6134449
- Report Number(s):
- ORNL/TM-11545; ON: DE91010487; TRN: 91-009571
- Country of Publication:
- United States
- Language:
- English
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Characteristics of edge plasma turbulence on the ATF torsatron
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Related Subjects
ATF TORSATRON
TURBULENCE
ECR HEATING
ELECTRON DENSITY
ELECTRON TEMPERATURE
FLUCTUATIONS
LANGMUIR PROBE
PLASMA DENSITY
WAVE PROPAGATION
CLOSED PLASMA DEVICES
ELECTRIC PROBES
HEATING
HIGH-FREQUENCY HEATING
PLASMA HEATING
PROBES
STELLARATORS
THERMONUCLEAR DEVICES
TORSATRON STELLARATOR
VARIATIONS
700101* - Fusion Energy- Plasma Research- Confinement
Heating
& Production
700102 - Fusion Energy- Plasma Research- Diagnostics