Scanning ion sensitive probe for plasma profile measurements in the boundary of the Alcator C-Mod tokamak

Brunner, D.; LaBombard, B.; Ochoukov, R.; Whyte, D.G.

doi:10.1063/1.4807699

Cited by 10 publications

(19 citation statements)

References 51 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…1, a collection of T i /T e measurements from a number of tokamak SOL has been examined for measurements taken before 2010, showing values that range from the lower T i /T e $ 1 to the extreme T i /T e $ 10, with most of the data falling between 1 and 4. More recent measurements, in HL-2A, 3 in MAST, 2,4 in Alcator C-MOD, 7,8 and in ASDEX Upgrade 6 have confirmed these findings. The ion temperature is therefore usually higher than the electron one in the SOL.…”

Section: Introductionsupporting

confidence: 70%

See 1 more Smart Citation

Finite ion temperature effects on scrape-off layer turbulence

et al. 2015

View full text Add to dashboard Cite

Ion temperature has been measured to be of the same order, or higher, than the electron temperature in the scrape-off layer (SOL) of tokamak machines, questioning its importance in determining the SOL turbulent dynamics. Here, we present a detailed analysis of finite ion temperature effects on the linear SOL instabilities, such as the resistive and inertial branches of drift waves and ballooning modes, and a discussion of the properties of the ion temperature gradient (ITG) instability in the SOL, identifying the g i ¼ L n =L T i threshold necessary to drive the mode unstable. The non-linear analysis of the SOL turbulent regimes by means of the gradient removal theory is performed, revealing that the ITG plays a negligible role in limited SOL discharges, since the ion temperature gradient is generally below the threshold for driving the mode unstable. It follows that the resistive ballooning mode is the prevailing turbulence regime for typical limited SOL parameters. The theoretical estimates are confirmed by non-linear flux-driven simulations of SOL plasma dynamics. [http://dx

show abstract

Section: Introductionsupporting

confidence: 70%

“…1 and references therein for a review of measurements before 2010, and Refs. 2-6 for more recent experimental campaigns), also other techniques are employed, such as the charge-exchange recombination spectroscopy, 7 the ion sensitive probe, 8 or the pinhole probe. 9 In Ref.…”

Section: Introductionmentioning

confidence: 99%

Finite ion temperature effects on scrape-off layer turbulence

et al. 2015

View full text Add to dashboard Cite

show abstract

“…There are two ion sensitive probes (ISP) on both sides of the middle stage, with pin 10 (12) as guard and pin 11 (13) as ion current collector. When both the guard and collector are biased with a sweeping voltage, it is able to measure the ion temperature [29][30][31]. The height and voltage difference between the guard and collector are two key parameters for the ISP.…”

Section: Methodsmentioning

confidence: 99%

The effects of magnetic topology on the scrape-off layer turbulence transport in the first divertor plasma operation of Wendelstein 7-X using a new combined probe

et al. 2019

View full text Add to dashboard Cite

Wendelstein 7-X (W7-X) was operated successfully with the first divertor plasma in the operation phase 1.2a (OP1.2a). A new combined probe head, developed and installed on the multiple-purpose manipulator, is able to measure the edge plasma profiles (𝑇 𝑒 , 𝑛 𝑒 , 𝜙 𝑓 , 𝑀 ∥ ), variation of magnetic field, poloidal and radial turbulence structures. The scrape-off layer (SOL) plasma parameters in two magnetic configurations (standard and high mirror) are in good agreement with the magnetic island structure and the field line connection length calculated by the field line tracer. In both the standard and high mirror configurations, the radial turbulent heat flux and particle flux have strong dependence on the local magnetic topology, revealing two distinct transport patterns: a broadband turbulence dominant region in the outer SOL and a low frequency dominant region in the inner SOL. In the standard divertor configuration, the broadband turbulence with a frequency range of 40-120 kHz is located near the island center along the probe path, leading to outward transport. These broadband fluctuations propagate with a velocity of 2.3-4.4 km/s poloidally along the ion diamagnetic drift direction in the plasma frame, with 𝑘 𝜃 𝜌 𝑠 close to 0.1. The large radial transport induced by the broadband turbulence is accompanied by a steep electron density gradient. The low frequency (5-30 kHz) dominant transport exhibits obvious intermittent structure. Some statistical techniques are applied to the characterization of the intermittent transport.

show abstract

“…Figure 3 shows the biasing voltage, the total current of the guard ring together with the correction for the capacity effect and the true collection current signal. A fourier technique [7] was used to correct the capacity effects that are present in the electronics. The originally collected current appears to have a phaseshift to the biasing voltage by about 90 • .…”

Section: Probe Measurementsmentioning

confidence: 99%

Operation of probe heads on the Multi-Purpose-Manipulator at W7-X in OP 1.2a

Drews

Killer

Knieps

et al. 2019

Fusion Engineering and Design

View full text Add to dashboard Cite

The MultiPurpose -Manipulator (MPM) has been operated, as a versatile carrier system for probes, since the first campaign OP. 1.1 in 2015 at Wendelstein 7X. The MPM is mounted at the outboard midplane and is able to perform fast plunges through the entire scrape off layer up to the last closed flux surface. In addition, a system for gas injection was commissioned that allowed the use of a dedicated probe head and a port on the existing probes for fueling and impurity seeding experiments. A combined probe, a combination of Langmuir, Mach and magnetic probes, was used. For the second campaign OP. 1.2a in 2017, with an island divertor, an upgraded combined probe, a fluctuation probe, a retarding field analyzer, a Mach probe array, a laser blow off target and a material probe holder were added to the range of plasma edge diagnostics. The new diagnostic probe heads were designed to address specific tasks, such as measuring the edge fluctuations, the ion temperature and the radial Mach number profiles. However, all fast plunging probes were designed such that they provide the most important quantities for SOL characterization (electron temperature, density, radial electric field).

show abstract

Scanning ion sensitive probe for plasma profile measurements in the boundary of the Alcator C-Mod tokamak

Cited by 10 publications

References 51 publications

Finite ion temperature effects on scrape-off layer turbulence

Finite ion temperature effects on scrape-off layer turbulence

The effects of magnetic topology on the scrape-off layer turbulence transport in the first divertor plasma operation of Wendelstein 7-X using a new combined probe

Operation of probe heads on the Multi-Purpose-Manipulator at W7-X in OP 1.2a

Contact Info

Product

Resources

About