#### P. A. Schneider C. Angioni F. Auriemma N. Bonanomi T. Görler R. Henriques L. Horvath D. King H. Nyström M. Maslov J. Ruiz G. Szepesi C. Challis E. Delabie J. M. Fontdecaba L. Frassinetti G. Garcia C. Giroud J. Hillesheim J. Hobirk A. Kappatou D. L. Keeling M. Lennholm B. Lomanowski T. Luda di Cortemiglia R. Lorenzini C. F. Maggi S. Menmuir A. Thorman

During the DTE2 campaign in the JET tokamak we performed a parameter scan in T and D-T complementing existing pulses in H and D. For the different main ion masses H-modes at fixed plasma current and magnetic field can have the pedestal pressure varying by a factor of 4 and the total pressure changing from betaN = 1.0 to 3.0. Based on this wide data…

Preprint#### E.R. Solano G. Birkenmeier C. Silva E. Delabie J.C. Hillesheim A. Baciero I. Balboa M. Baruzzo A. Boboc M. Brix C. Bourdelle I.S. Carvalho P. Carvalho C.D. Challis M. Chernyshova A. Chomiczewska R. Coelho T. Craciunescu E. de la Cal E. de la Luna R. Dumont P. Dumortier M. Fontana J.M. Fontdecaba L. Frassinetti D. Gallart J. Garcia C. Giroud W. Gromelski R.B. Henriques J. Hall A. Ho L. Horvath P. Jacquet I. Jepu E. Joffrin A. Kappatou P.J. Lomas D.L. Keeling D.B. King E. Kowalska-Strzęciwilk M. Lennholm E. Lerche E. Litherland-Smith V.G. Kiptily K.K. Kirov A. Loarte B. Lomanowski C.F. Maggi J. Mailloux M.J. Mantsinen M. Maslov A.G. Meigs I. Monakhov R.B. Morales A.H. Nielsen D. Nina C. Noble E. Pawelec M. Poradzinski G. Pucella P. Puglia D. Réfy J.J. Rasmussen E. Righi-Steele F.G. Rimini T. Robinson M. Sertoli S.A. Silburn P. Sirén Ž. Štancar H.J. Sun G. Szepesi D. Taylor B. Thomas E. Tholerus G. Verdoolaege P. Vincenzi B. Viola N. Vianello T. Wilson

Preprint Published

#### V.H. Hall-Chen F.I. Parra J.C. Hillesheim J. Ruiz Ruiz N.A. Crocker P. Shi H.S. Chu S.J. Freethy L.A. Kogan W.A. Peebles Q.T. Pratt T.L. Rhodes K. Ronald R. Scannell D.C. Speirs S. Storment J. Trisno

Doppler reflectometry, or the Doppler backscattering (DBS) diagnostic, enables the measurement of turbulent density fluctuations of intermediate length scales, typically $10 gtrsim k_perp rho_i gtrsim 1$; here $k_perp$ is the turbulence’s wavenumber and $rho_i$ is the ion gyroradius. The backscattered power is proportional to the power of the tur…

Preprint#### V.H. Hall-Chen J. Damba F.I. Parra Q.T. Pratt C.A. Michael S. Peng T.L. Rhodes N.A. Crocker J.C. Hillesheim R. Hong S. Ni W.A. Peebles C.E. Png J. Ruiz Ruiz

We use the beam model of Doppler backscattering (DBS), which was previously derived from beam tracing and the reciprocity theorem, to shed light on mismatch attenuation. This attenuation of the backscattered signal occurs when the wavevector of the probe beam’s electric field is not in the plane perpendicular to the magnetic field. Correcting …

Published#### B. Chapman D.R. Hatch A.R. Field L. Frassinetti J.C. Hillesheim L. Horvath C.F. Maggi J. F. Parisi C.M. Roach S.Saarelma J. Walker JET contributors

We present the results of GENE gyrokinetic calculations based on a series of JET-ILW type I ELMy H-mode discharges operating with similar experimental inputsbut at different levels of power and gas fuelling. We show that turbulence due to slab electron-temperature-gradient modes (sETGs) produces a significant amount of heat flux in four JET-ILW …

Published#### V. H. Hall-Chen F. I. Parra J. C. Hillesheim

We use beam tracing — implemented with a newly-written code, Scotty — and the reciprocity theorem to derive a model for the linear backscattered power of the Doppler Backscattering (DBS) diagnostic. Our model works for both the O-mode and X-mode in tokamak geometry (and certain regimes of stellarators). We present the analytical derivation of o…

Preprint Published#### J.C. Hillesheim E. Delabie E. Solano C.F. Maggi H. Meyer E. Belonohy I. Carvalho E. de la Luna A. Drenik M. Gelfusa C. Giroud J. Hobirk A.E. Hubbard A. Kappatou H.T. Kim A. Huber E. Lerche B. Lomanowski M. Mantsinen S. Menmuir I. Nunes E. Peluso F. Rimini P.A. Schneider M. Stamp G. Verdoolaege JET Contributors

Unraveling the conditions that permit access to H-mode continues to be an unresolved physics issue for tokamaks, and accurate extrapolations are important for planning ITER operations and DEMO design constraints. Experiments have been performed in JET, with the ITER-like W/Be wall, to increase the confidence of predictions for the L-H transition po…

Preprint Published#### J F Parisi F I Parra C M Roach C Giroud W Dorland D R Hatch M Barnes J C Hillesheim N Aiba J R Ball P G Ivanov

Local linear gyrokinetic simulations show that electron temperature gradient (ETG) instabilities are the fastest growing modes for kyρi >~ 0.1 in the steep gradient region for a JET pedestal discharge (92174) where the electron temperature gradient is steeper than the ion temperature gradient. Here, ky is the wa…

Preprint Published#### D. B. King E. Viezzer I. Balboa M. Baruzzo E. Belonohy J. Buchanan I.S. Carvalho K. Cave-Ayland I. Coffey C.D. Challis E.G. Delabie L. Garzotti S. Hall J.Hillesheim L. Horvath E. Joffrin D. Keeling K. Kirov C.F. Maggi M. Maslov S. Saarelma S. Silburn E.R. Solano M. Stamp D. Valcarcel H.Weisen

A study of mixed hydrogen-deuterium H-mode plasmas has been carried out in JET-ILW to strengthen the physics basis for extrapolations to JET D-T operation and to support the development of strategies for isotope ratio control in future experiments. Variations of input power, gas fuelling and isotopic mixture were performed in H-mode plasmas of the…

Preprint Published#### V.H. Hall-Chen F.I. Parra J.C. Hillesheim

The use of Doppler Backscattering (DBS) in spherical tokamaks is challenging since the magnetic pitch angle can be large (up to 35, compared to 15 in standard tokamaks like JET). Moreover the pitch angle varies both spatially and temporally. Hence, the probe beam is generally not perpendicular to the magnetic field. This misalignment, which affec…

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