Characterization of local heat fluxes around ICRF antennas on JET

Campergue, A. L.; Jacquet, P.; Bobkov, V.; Milanesio, Daniele; Monakhov, I.; Colas, L.; Arnoux, G.; Brix, M.; Sirinelli, A.; Contributors, Jet

doi:10.1063/1.4864538

Cited by 7 publications

(9 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The peak heat load onto the plasma facing components of tokamak devices depends on the scrape-off layer (SOL) width [1][2][3][4][5][6][7][8][9], which results from a balance between plasma injection from the core region, turbulent transport, and losses to the divertor or limiter. While determining the SOL width and understanding the transport mechanism involved are critical issues for ITER and all future tokamak devices, so far there are no first-principle methods from the theory to predict the SOL width even for the simplest circular, limited plasmas.…”

mentioning

confidence: 99%

Theory-based scaling of the SOL width in circular limited tokamak plasmas

et al. 2013

View full text Add to dashboard Cite

A theory-based scaling for the characteristic length of a circular, limited tokamak scrape-off layer (SOL) is obtained by considering the balance between parallel losses and non-linearly saturated resistive ballooning mode turbulence driving anomalous perpendicular transport. The SOL size increases with plasma size, resistivity, and safety factor q. The scaling is verified against flux-driven non-linear turbulence simulations, which reveal good agreement within a wide range of dimensionless parameters, including parameters closely matching the TCV tokamak. An initial comparison of the theory against experimental data from several tokamaks also yields good agreement.

show abstract

mentioning

confidence: 99%

Theory-based scaling of the SOL width in circular limited tokamak plasmas

et al. 2013

View full text Add to dashboard Cite

show abstract

“…38 Although ICRF heating was used in the H-mode plasmas only late in the initial JET-ILW experimental campaign, we have indications that this tool can be used in JET-ILW to prevent impurity accumulation. This is pictured in Figures 16-18 for pulse 83897 (B T ¼ 2.65 T, I P ¼ 2MA, 16.0 MW NBI) and pulse 83603 (same plasma, 14.4 MW NBI and 3.4 MW ICRF heating). Due to the slightly lower NBI power in 83603, the ELM are less frequent before the ICRF phase and impurity flushing by the ELMs at the edge transport barrier is less efficient, hence the increased total radiated power for 83603 at the beginning of the H-mode phase.…”

Section: B Icrf Heating Performancementioning

confidence: 86%

“…We have tested a simple RF sheath rectification model, in particular, to verify if the intensity and the location of the hot-spots measured on the JET antenna protecting limiters is consistent with the E // map in front of the A2s as calculated using the TOPICA code (E // is the RF electric field that drive RF sheath rectification, // denotes the direction parallel to static magnetic field). 16 In the simplified model derived from Ref. 17, Q // ¼ e Z n c s V DC where e is the elementary charge, Z is the atomic number of plasma ions (D þ ), c s is the ion sound speed in the SOL, n is the electron density at the antenna and…”

Section: B Icrf Specific Heat Loads On Antenna Limitersmentioning

confidence: 99%

See 1 more Smart Citation

Ion cyclotron resonance frequency heating in JET during initial operations with the ITER-like wall

et al. 2014

Self Cite

View full text Add to dashboard Cite

Équipe 107 : Physique des plasmas chaudsInternational audienceIn 2011/12, JET started operation with its new ITER-Like Wall (ILW) made of a tungsten (W) divertor and a beryllium (Be) main chamber wall. The impact of the new wall materials on the JET Ion Cyclotron Resonance Frequency (ICRF) operation is assessed and some important properties of JET plasmas heated with ICRF are highlighted. A similar to 20% reduction of the antenna coupling resistance is observed with the ILW as compared with the JET carbon (JET-C) wall. Heat-fluxes on the protecting limiters close the antennas, quantified using Infra-Red thermography (maximum 4.5MW/m(2) in current drive phasing), are within the wall power load handling capabilities. A simple RF sheath rectification model using the antenna near-fields calculated with the TOPICA code can reproduce the heat-flux pattern around the antennas. ICRF heating results in larger tungsten and nickel (Ni) contents in the plasma and in a larger core radiation when compared to Neutral Beam Injection (NBI) heating. The location of the tungsten ICRF specific source could not be identified but some experimental observations indicate that main-chamber W components could be an important impurity source: for example, the divertor W influx deduced from spectroscopy is comparable when using RF or NBI at same power and comparable divertor conditions, and Be evaporation in the main chamber results in a strong reduction of the impurity level. In L-mode plasmas, the ICRF specific high-Z impurity content decreased when operating at higher plasma density and when increasing the hydrogen concentration from 5% to 15%. Despite the higher plasma bulk radiation, ICRF exhibited overall good plasma heating performance; the power is typically deposited at the plasma centre while the radiation is mainly from the outer part of the plasma bulk. Application of ICRF heating in H-mode plasmas has started, and the beneficial effect of ICRF central electron heating to prevent W accumulation in the plasma core has been observed

show abstract

“…We have tested a simple RF sheath rectification model in particular to verify if the intensity and the location of the hot-spots measured on the JET antenna protecting limiters is consistent with the E // map in front of the A2s as calculated using the TOPICA code (E // is the RF electric field that drive RF sheath rectification, // denotes the direction parallel to static magnetic field) [12]. In the simplified model derived from [13],…”

Section: A2 Antenna Operation and Rf/sol Interactionmentioning

confidence: 97%

ICRF heating in JET during initial operations with the ITER-like wall

Jacquet

Bobkov

Brezinsek

et al. 2014

AIP Conference Proceedings

Self Cite

View full text Add to dashboard Cite

In 2011/12, JET started operation with its new ITER-Like Wall (ILW) made of a tungsten (W) divertor and a beryllium (Be) main chamber wall. The impact of the new wall material on the JET Ion Cyclotron Resonance Frequency (ICRF) operation was assessed and also the properties of JET plasmas heated with ICRF were studied. No substantial change of the antenna coupling resistance was observed with the ILW as compared with the carbon wall. Heat-fluxes on the protecting limiters close the antennas quantified using Infra-Red (IR) thermography (maximum 4.5 MW/m 2 in current drive phasing) are within the wall power load handling capabilities. A simple RF sheath rectification model using the antenna near-fields calculated with the TOPICA code can well reproduce the heat-flux pattern around the antennas. ICRF heating results in larger tungsten and nickel (Ni) contents in the plasma and in a larger core radiation when compared to Neutral Beam Injection (NBI) heating. Some experimental facts indicate that main-chamber W components could be an important impurity source: the divertor W influx deduced from spectroscopy is comparable when using RF or NBI at same power and comparable divertor conditions; the W content is also increased in ICRF-heated limiter plasmas; and Be evaporation in the main chamber results in a strong and long lasting reduction of the impurity level. The ICRF specific high-Z impurity content decreased when operating at higher plasma density and when increasing the hydrogen concentration from 5% to 20%. Despite the higher plasma bulk radiation, ICRF exhibited overall good plasma heating efficiency; The ICRF power can be deposited at plasma centre and the radiation is mainly from the outer part of the plasma. Application of ICRF heating in H-mode plasmas started, and the beneficial effect of ICRF central electron heating to prevent W accumulation in the plasma core could be observed.

show abstract

Characterization of local heat fluxes around ICRF antennas on JET

Cited by 7 publications

References 9 publications

Theory-based scaling of the SOL width in circular limited tokamak plasmas

Theory-based scaling of the SOL width in circular limited tokamak plasmas

Ion cyclotron resonance frequency heating in JET during initial operations with the ITER-like wall

ICRF heating in JET during initial operations with the ITER-like wall

Contact Info

Product

Resources

About