A. Canton, S. Dal Bello 13 th IEA/RFP Workshop Density control in RFX-mod A. Canton, S. Dal Bello Consorzio RFX, Padova, Italy.

Slides:



Advertisements
Similar presentations
How to do wall conditioning in ITER ? # B tor cycles is limited GDC inefficient in B Drawbacks of ECWC, Taylor Ion cyclotron wall conditioning (ICWC) J.
Advertisements

V.Philipps, SEWG Gas balance and fuel removal, JET, , Association EURATOM – FZJ Effect of disruptions on fuel release from JET walls V. Philipps,
1B. PégouriéDITS progress report 27/04/07 Euratom EXPERIMENTAL CAMPAIGN No reliable estimation of the wall inventory WI ~ ??? D atoms (Tsitrone,
14th IEA RFP Workshop – Padova, April 26th-28th 2010 RFX-mod thermal measurement system: a possible diagnostic for plasma-wall interaction M. Dalla Palma.
Development of experimental devices to study first wall conditioning and transport phenomena in RFX-mod experiment Stefano Munaretto Università degli studi.
XP 1157 Increasing the CHI start-up current magnitude in NSTX B.A. Nelson et al. 1.
M. Zuin RFX ws 2011 Padova, 7-9/2/2011 Innovative contributions to confinement understanding M. Zuin.
ICC2004 Madison, Wisconsin The Multi-Pinch Experiment Outline PROTO-SPHERA purpose & aims Theoretical basis & analysis Multi-Pinch: a step towards PROTO-SPHERA.
The Reversed Field Pinch: on the path to fusion energy S.C. Prager September, 2006 FPA Symposium.
RFP Workshop, Stockholm 9-11 /10/ 2008 Numerical studies of particle transport mechanisms in RFX-mod low chaos regimes M.Gobbin, L.Marrelli, L.Carraro,
Y. Ueda, M. Fukumoto, H. Kashiwagi, Y. Ohtsuka (Osaka University)
MHD Behaviour of Low-Aspect-Ratio RFP Plasmas in RELAX S.Masamune, T.Onchi, A.Sanpei, R.Ikezoe, K.Oki, T.Yamashita, H.Shimazu, N.Nishino 1), R.Paccagnella.
A.Karpushov, Mission 410, Jaunt 414,  p "H-gas puff experiments on TCV" Réunions scientifiques, 22 novembre 2004  p 414-1: “H-gas puff experiments.
13th IEA/RFP Workshop – Stockholm October 9-11, D characterization of thermal core topology changes in controlled RFX-mod QSH states A. Alfier on.
Plasma Dynamics Lab HIBP Abstract Measurements of the radial equilibrium potential profiles have been successfully obtained with a Heavy Ion Beam Probe.
Spatial profiles of copper atom density in a Cu/Ne hollow cathode discharge P. Hartmann*, T.M. Adamowicz**, E. Stoffels and W.W. Stoffels, Department of.
L. Zanotto, 13th RFP Workshop, Stockholm10/10/2008 Similarity experiments on RFX-mod and MST standard discharges: magnetics T. Bolzonella, P. Franz, D.
HEAT TRANSPORT andCONFINEMENTin EXTRAP T2R L. Frassinetti, P.R. Brunsell, M. Cecconello, S. Menmuir and J.R. Drake.
Physics of fusion power Lecture 10 : Running a discharge / diagnostics.
S.C. Guo 13th IEA/RFP Workshop, October 9-11, 2008, Stockholm 1 Experiments and modeling on active RWM rotation in RFP plasmas S.C. Guo, M. Baruzzo, T.
ECE/ChE 4752: Microelectronics Processing Laboratory
RFX-mod Workshop – Padova, January Experimental QSH confinement and transport Fulvio Auriemma on behalf of RFX-mod team Consorzio RFX, Euratom-ENEA.
Plasma particle fuelling a general view of methods and issues David Terranova.
A. Alfier – RFX-mod PROGRAMME WORKSHOP 2009 – 20/22 Jan 2009 Density issues & Lithization in RFX-mod A. Alfier, A. Canton, R. Cavazzana, S. Dal Bello,
pkm- NCSX CDR, 5/21-23/ Power and Particle Handling in NCSX Peter Mioduszewski 1 for the NCSX Boundary Group: for the NCSX Boundary Group: M. Fenstermacher.
RFX-mod 2009 programme Workshop, January 20-22, 2009 Report on experimental proposals submitted to TF1 ‘RFP performance: high current operation and advanced.
Measurement and modeling of hydrogenic retention in molybdenum with the DIONISOS experiment G.M. Wright University of Wisconsin-Madison, FOM – Institute.
ASIPP In-time retention evaluation by particle balance analysis on HT-7 Y. YANG*, and HT-7 team Institute of Plasma Physics, Chinese Academy of Sciences.
Profile Measurement of HSX Plasma Using Thomson Scattering K. Zhai, F.S.B. Anderson, J. Canik, K. Likin, K. J. Willis, D.T. Anderson, HSX Plasma Laboratory,
14 th IEA-RFP Workshop, Padova 26 th -28 th April 2010 The SHEq code: an equilibrium calculation tool for SHAx states Emilio Martines, Barbara Momo Consorzio.
V. A. Soukhanovskii 1 Acknowledgements: M. G. Bell 2, R. Kaita 2, H. W. Kugel 2, R. Raman 3, A. L. Roquemore 2 1 Lawrence Livermore National Laboratory,
R. Piovan “RFX-mod: what does...”RFX 2009 Programme Workshop Padova, Jan RFX – mod: what does the present device allow to do? R. Piovan.
Rotation effects in MGI rapid shutdown simulations V.A. Izzo, P.B. Parks, D. Shiraki, N. Eidietis, E. Hollmann, N. Commaux TSD Workshop 2015 Princeton,
TIME-RESOLVED OPTICAL SPECTROSCOPY OF HIGH-TEMPERATURE PLASMAS M.J. Sadowski  , K. Malinowski , E. Skladnik-Sadowska , M. Scholtz , A. Tsarenko ¤
RFX-mod Programme Workshop 2009 – January 2009 Scaling and validation plans Paolo Franz, Monica Spolaore.
H. W. Kugel 45 th APS DPP Meeting Oct 27-31, 2003, Albuquerque, NM 1 Lithium Experiments in the NSTX Boundary Physics Program H.W.Kugel, M.Bell, R.Kaita,
Introduction to Plasma- Surface Interactions Lecture 3 Atomic and Molecular Processes.
QSH/SHAx states: towards the determination of an helical equilibrium L. Marrelli acknowledging fruitful discussions with S.Cappello, T.Bolzonella, D.Bonfiglio,
RFX-mod programme workshop 2011 February 7 - 9, 2011 Wall conditioning techniques: status and perspectives S.Dal Bello, A.Canton, L.Grando, P.Innocente,
Plasma-wall interactions during high density operation in LHD
CHI Run Summary for March 10-12, 31 & April 9, 2008 Flux savings from inductive drive of a Transient CHI started plasma (XP817) R. Raman, B.A. Nelson,
ASIPP In-time retention evaluation by particle balance analysis on HT-7 Y. YANG*, and HT-7 team Institute of Plasma Physics, Chinese Academy of Sciences.
Background Long term tritium retention is one of the most critical issues for ITER during the tritium phase. It is mandatory to evaluate the long term.
EAST ASIPP ICR-Wall conditioning in EAST J.S Hu, J.G Li and EAST Team Institute of Plasma Physics, Chinese Academy of Sciences, P.O.Box 1126, Hefei, Anhui.
Behaviour of Runaway Electrons during Injection of High Z Impurities/Gas Puffing in HT-7 S.Sajjad INSTITUTE OF PLASMA PHYSICS,HEFEI CHINA.
Session I-B – Overview Talks Lithium in Magnetic Confinement Experiments S. MirnovLi collection experiments on T-11M and T-10 in framework of Li closed.
Compression Ignition Engines
EFDA EUROPEAN FUSION DEVELOPMENT AGREEMENT Task Force S1 J.Ongena 19th IAEA Fusion Energy Conference, Lyon Towards the realization on JET of an.
Measurements of plasma turbulence by laser scattering in the Wendelstein 7-AS stellarator Nils P. Basse 1,2, S. Zoletnik, M. Saffman, P. K. Michelsen and.
RFX workshop / /Valentin Igochine Page 1 Control of MHD instabilities. Similarities and differences between tokamak and RFP V. Igochine, T. Bolzonella,
PERSISTENT SURVEILLANCE FOR PIPELINE PROTECTION AND THREAT INTERDICTION International Plan for ELM Control Studies Presented by M.R. Wade (for A. Leonard)
L. Zanotto – 10 February 2011 – RFX-mod programme workshop TF2: Active control of RFP and tokamak plasmas Report on experimental proposals L. Zanotto,
RFX-mod Programme Workshop, 20-22/01/09, Padova - T. Bolzonella1 Tommaso Bolzonella on behalf of RFX-mod team Consorzio RFX- Associazione Euratom-ENEA.
RFX-mod programme workshop, January 2009 Scenario and operational issues for high current L. Zanotto, R. Cavazzana, S. Dal Bello, F. Milani.
Effect of Re Alloying in W on Surface Morphology Changes After He + Bombardment at High Temperatures R.F. Radel, G.L. Kulcinski, J. F. Santarius, G. A.
1 Feature of Energy Transport in NSTX plasma Siye Ding under instruction of Stanley Kaye 05/04/09.
T. Bolzonella – 9 February 2011 – RFX-mod programme workshop TF1: Physics integration for high performance RFP Proposals and discussion T. Bolzonella,
GOLEM operation based on some results from CASTOR
Solenoid Free Plasma Start-up Mid-Run Summary (FY 2008) R. Raman and D. Mueller Univ. of Wash. / PPPL 16 April 2008, PPPL 1 Supported by Office of Science.
1 Differential Residual Gas Analysis in the HT-7 Tokamak J.S Hu and HT-7 vacuum group Institute of Plasma Physics, Chinese Academic of Science, Hefei,
Brookhaven Science Associates U.S. Department of Energy MUTAC Review April , 2004, BNL Target Simulations Roman Samulyak in collaboration with Y.
Simulation of Turbulence in FTU M. Romanelli, M De Benedetti, A Thyagaraja* *UKAEA, Culham Sciance Centre, UK Associazione.
Radiation divertor experiments in the HL-2A tokamak L.W. Yan, W.Y. Hong, M.X. Wang, J. Cheng, J. Qian, Y.D. Pan, Y. Zhou, W. Li, K.J. Zhao, Z. Cao, Q.W.
Localised Neutron Emission at the edge of high density JET Trace Tritium - ELMy H-mode plasmas A.Murari 6 on the behalf of G. Bonheure 1, S. Popovichev.
56 th Annual Meeting of the Division of Plasma Physics. October 27-31, New Orleans, LA Using the single reservoir model [3], shown on right, to:
NIMROD Simulations of a DIII-D Plasma Disruption S. Kruger, D. Schnack (SAIC) April 27, 2004 Sherwood Fusion Theory Meeting, Missoula, MT.
Long-term environmental effects on the ARGO-YBJ RPC array studied with the Detector Control System P. CAMARRI 1, R. CARDARELLI 1, L. PALUMMO 1, C. VIGORITO.
Effects of external non-axisymmetric perturbations on plasma rotation L. Frassinetti, P.R. Brunsell, J.R. Drake, M.W.M. Khan, K.E.J. Olofsson Alfvén Laboratory,
SAWTOOTH AND M=1 MODE BEHAVIOUR IN FTU PELLET ENHANCED DISCHARGES
In-time retention evaluation by particle balance analysis on HT-7
Presentation transcript:

A. Canton, S. Dal Bello 13 th IEA/RFP Workshop Density control in RFX-mod A. Canton, S. Dal Bello Consorzio RFX, Padova, Italy

A. Canton, S. Dal Bello 13 th IEA/RFP Workshop Outline Introduction about RFX-mod Density behaviour in RFX-mod DESO: a diagnostic for the wall Dependence of plasma density on wall condition How to obtain a discharge with a desired plasma density on RFX-mod? Conclusions

A. Canton, S. Dal Bello 13 th IEA/RFP Workshop Introduction ● RFX-mod first wall is entirely made of graphite ● Gas fuelling methods available at RFX-mod: Pre-pulse gas filling During pulse gas puffing Pellet injection Wall preloading by means of H 2 GDC ● Wall treatment procedures: He GDC (performed on daily base or more) Baking + GDC cycles (3-5 per year) Boronization (1-3 per year) By a system of 8+8 piezoelectric valves installed at 4 toroidal positions Up to 8 pellet per shot with masses in the range 1.5-5x10 20 atoms

A. Canton, S. Dal Bello 13 th IEA/RFP Workshop Density behaviour in RFX-mod - 1 Vacuum vessel is filled with gas before the shot. A minimum pressure of about 0.3x10 -3 mbar allows breakdown. Before reversal particles are not confined and are lost to the wall. Time of reversal

A. Canton, S. Dal Bello 13 th IEA/RFP Workshop Density behaviour in RFX-mod - 2 RFX-mod first wall is an almost infinite reservoir of particles -> density at flat top (FT) is entirely sustained by particles fluxes from the wall -> it does not depend on the fuelled particles With a graphite wall density control requires to be able to control the status of the wall

A. Canton, S. Dal Bello 13 th IEA/RFP Workshop DESO diagnostic system We need to carefully control the particles both injected and extracted during the operations with plasma A new diagnostic tool, named DESO, has been implemented on RFX-mod. Aims: -> Improves the reproducibilty of the gas fuelling system a series of dummy openings of the valves (performed some minutes before the shot) stabilize their flow -> Computes the particles that fuel the discharge, both as filling and as puffing before the shot it executes the same opening of the valves programmed for the discharge and evaluates the number of particles entering the vessel by the measure of pressure -> Computes the neutral particles outgassed from the wall and extracted from the chamber after the shot

A. Canton, S. Dal Bello 13 th IEA/RFP Workshop One parameter adopted to describe the status of the wall is the Desorption factor Des% Extracted particles:-> evaluated by DESO Total fuelled particles: - By gas filling/puffing-> evaluated by DESO - By pellet injection-> pellet masses measured by the injector diagnostic system Desorption factor Des% Des% = __________________________________________________ * 100 Extracted particles after the end of the pulse Total fuelled particles Des% expresses, shot by shot, the capability of the wall of absorbing the fuelled particles

A. Canton, S. Dal Bello 13 th IEA/RFP Workshop Other two parameters: Particles left in the wall shot by shot: DeltaPart Particles stored in the wall at each shot: Total fuelled particles (filling, puffing, pellet injection,H 2 GDC) – Outgassed particles Particles stored in the wall by H 2 GDC are computed following experimental results found in literature, see Winter,J. Nucl. Mater.161 (1989), p.265) Particles removed from the wall by He GDC (computed by mass spectrometer measurements) Total number of particles stored in the wall since last Baking or Boronization procedure: TotPart Particles inventory in the wall DeltaPart = Particles stored in the wall (– Particles removed from the wall by GDC) TotPart = Σ DeltaPart

A. Canton, S. Dal Bello 13 th IEA/RFP Workshop Behaviour of TotPart and Des% Baking+GDC Number of particles to saturate the wall, assuming an implantation depth of the order of tens of nm [Tramontin et al., J. Nucl. Mater (1999), p.709] We are planning new experiments of samples exposition to the plasma in order to allow a better computation of the wall volume where particles are stored Daily He GDCs (20-60 min) remove 1-2x10 21 H atoms and allow operation, but they are not effective in preventing particle accumulation in the wall Des% alone is not an absolute indicator of saturation state for the wall. It depends on plasma parameters (e.g. current), plasma-wall interaction, wall temperature...

A. Canton, S. Dal Bello 13 th IEA/RFP Workshop Wall and density - 1 Absorbing wall: wide range of density regimes Not absorbing wall: I/N forced to the value 2x Am Wall condition affects density... Des% leads I/N No correlation found between Des% and ne or I alone...but plasma itself extracts particles from the wall (PWI) Density depends on Ohmic Power, that regulates particle influxes from the wall Analysis over a database of about 700 shots. Quantities averaged over 2ms around max plasma current. 0.3<I<1.6 MA, 1<ne< m -3

A. Canton, S. Dal Bello 13 th IEA/RFP Workshop Wall and density - 2 No dependence of density and/or I/N on the total number of particles stored in the wall Where are the particles stored? Implantation depth, toroidal and poloidal asymmetries can cause that stored particles are not accessible by plasma.

A. Canton, S. Dal Bello 13 th IEA/RFP Workshop About particles inventory in the wall In RFX-mod we outgas a minimum part of the particles that we inject Outgassed particles depend (only?) on the temperature of the wall: limited to <100°C To avoid particles accumulation in the wall we should always fuel the discharge with the minimum gas to allow breakdown

A. Canton, S. Dal Bello 13 th IEA/RFP Workshop How to obtain a discharge with a desired plasma density? - Control particle fluxes from the wall Control PWIWith respect to RFX, the improved control of magnetic boundary (lower error fields and rotating modes) and a new design of the graphite tiles has allowed the operation of RFX-mod up to 1.6 MA - Control the status of the wall It means to control both particle content and their spatial distribution in the wall Optimization of He GDC with respect to the plasma to be done - Effectively fuel the discharge Gas Filling-> useless: between breakdown and reversal the particles are lost and stored in the wall Gas Puffing-> on RFX-mod proved to be inefficient due to the low flow and gas velocity of the piezo valves: neutral particles do not penetrate the plasma and accelerate particle accumulation in the wall Pellet injection-> density can be transiently raised but density control is quickly lost because of the large amount of injected particles that are left on the wall

A. Canton, S. Dal Bello 13 th IEA/RFP Workshop H 2 GDC as a way to obtain reproducible plasma density Wall pre-loading by means of H 2 GDC is under test as a reproducible method to obtain a discharge with desired flat top density. -> Technique originally developed as a way to condition the wall after heavy treatments like boronisation. -> The same technique tentatively applied after the morning He GDC. Reproducible correspondence between the number of implanted particles and the obtained plasma density, even if there is a factor 10 between the two. Optimization in progress -> At the maximum explored plasma currents I~1.5 MA the effect of pre-load lasts for only one shot, at I<1MA it lasts for several shots (of the order of 10) The influence on the duration of the pre-load treatment of the voltage applied to the GDC anodes, that determines the energy and hence the depth of the particles implanted in the wall during the H2 GDC, and of the implant fluence that influences the depth profile, is under test.

A. Canton, S. Dal Bello 13 th IEA/RFP Workshop Conclusions In RFX-mod density control is strongly influenced by the wall A new diagnostic tool, DESO, has been recently implemented. On the one side it is devoted to increase the reproducibility of the gas fueling system, on the other side it allows to precisely compute the particles stored in the wall and to characterise its behaviour The relation between plasma density and wall condition has been explored over a large database of pulses. The capability of the wall to absorb particles, described by the desorption factor Des%, was found to influence the value of I/N more than the absolute number of particles stored in the wall The strength of plasma wall interaction was found to be the other factor that determines plasma density, confirming the importance of the control of PWI in particular in view of operation at 2 MA in the next future of RFX-mod H 2 GDC is a promising way to obtain reproducible plasma density but the techinque need to be optimised

A. Canton, S. Dal Bello 13 th IEA/RFP Workshop Wall and density - extras