Warming and Current Drive Studies In the ARIES Program T.K. Mau University of California, San Die

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´╗┐Warming and Current Drive Studies In the ARIES Program T.K. Mau University of California, San Diego Peer Review of the ARIES Program August 17, 2000 University of California, San Diego

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Heating and Current Drive Analysis is Critical Determine and comprehend current drive control prerequisite, a basic component in frameworks examination for the power plant COE. Select most practical current drive plans for keeping up superior, MHD-stable plasma equilibria, as indicated by: 1. Center openness 2. Current drive effectiveness 3. Profile control capacity 4. Experimental information base and material science understanding 5. Control era productivity 6. Double ability of current drive and helper plasma warming 7. Center similarity of in-vessel parts. Decide current drive source and power launcher prerequisites, e.g., frequency and range for RF launchers, beam vitality and infusion plot for NBI frameworks. Distinguish (and resolve) issues and ranges for further research.

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RF Heating and Current Drive Analysis for ARIES Motivates Extension of Physics Models to Power Plant Regimes Main examination is the CURRAY beam following code (created with GA), with cutting edge highlights: Wave retention material science : - Cold particle (k x r i << 1), warm electron scattering connection - Thermal particle and electron impacts in field polarization terms while computing direct damping decrement along beams - Energetic particle species (e.g., alphas) are dealt with either as hot Maxwellian or having backing off conveyance - Calculates assimilation profiles, because of cyclotron reverberation, Landau and TTMP forms, for all species Current drive material science : - Calculates nearby determined electron streams - Developed standardized j/p effectiveness recipes due to Ehst-Karney and Chiu-Mau (relativistic revision) - Extended j/p scaling to low viewpoint proportion administrations [ARIES-ST, NSTX] [ A component interesting to CURRAY ] - Developed calculation to amplify arrangement of headed to harmony j-profile Coupled to high-accuracy balance geometry (JSOLVER)

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Overview of Current Drive Scenarios for ARIES Power Plants ARIES-AT requires significantly less present drive control than ARIES-RS due to much better bootstrap arrangement. Device ARIES-RS ARIES-ST ARIES-AT R (m) 5.5 3.2 5.2 A 4.0 1.6 4.0 I p (MA) 11.3 28.4 12.8 b (%) 5.0 50.4 9.2 I bs/I p 0.88 0.96 0.915 On-pivot CD* ICRF/FW Potato Orbit ICRF/FW Off-hub CD* HHFW,LHW NBI(120 keV) LHW Power (MW) 82.0 27.6 35.0 * ECCD can be restricted at all radii, however was not utilized here because of low current drive and source efficiencies.

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Target Equilibrium Can be Maintained with RF-and Self-Driven Currents Self-driven current [= bootstrap + diamagnetic + Pfirsch-Schlutter] is ascertained for different particle species for all collisional administrations on correct harmony and self-reliable (p, n, T) profiles. 2 RF plans are required to drive the seed streams on ARIES-AT: (I) ICRF quick waves for on-hub drive; (2) LH waves for off-pivot drive. ARIES-AT Driven ARIES-AT Driven EQ BS - <j f > ( A/cm 2 ) BS Driven LHCD Dia+P.S. Dia + PS FWCD r

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Frequency Options for Fast Wave On-Axis CD Criteria : Avoid particle and an ingestion no reverberation on OB side Reasonable recieving wire measure higher recurrence 68 MHz, 96 MHz, and 135 MHz seem possible; comparable power prerequisites Use 68 MHz as reference in ARIES-AT. Particle Resonant Frequencies R+a R-a 5T 4D,6T 3D 4T 135 MHz 2D,3T 96 MHz 2T Frequency (MHz) 68 MHz D T 22 MHz ARIES-AT Axis Major Radius (m)

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ICRF Fast Wave Drives On-hub Seed Current Axis Wave recurrence is put 2f cD reverberation at R > R o +a, and 2f cT reverberation at R << R pivot , to maintain a strategic distance from particle and alpha retention. Launcher is situated on detachable midplane with N || = 2 range for best current profile arrangement. Plasma & wave parameters : R = 5. 2 m, A = 4, k = 2.2, d =0.8, B o = 5.9 T, I p = 13 MA, b N = 6.0, T eo = 29 keV, n eo,20 = 2.95, Z eff = 1.8 f = 68 MHz, N || = - 2.0. Y (m) Z (m) X (m) R (m) ARIES-AT P e/P = 0.94 P T/P = 0.03 P a/P = 0.03 Power Absorption ( W/cm 3 ) electrons T, a r

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LH Wave Penetration is an Issue in High-b Plasmas Frequency = 3.6 GHz [ > 2 x f LH ( r =0.8) ] - Less than 1% a retention, despite the fact that f=9.3 GHz to dispense with a - damping. There is a window in N || for availability to the center: [ 1 + (f pe/f ce ) 2 ] 1/2 + f pe/f ce < N || < 7.0/T e 1/2 (keV) Penetration is restricted to r > 0.8 for the high-b AT balance . [ b ~ (f pe/f ce ) 2 ] Low N || beams experience mode transformation to quick wave at r > 0.8 and proliferates back to edge; higher N || beams get completely damped before achieving r = 0.8. Openness of LH Waves Axis Inaccessible Accessible N || = - 1.6 Accessible ARIES-AT b = 9.2% e-damping limit End Window of Accessibility, N || Z (m) Start MC constrain R (m)

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Off-Axis Current Drive Requires Tailored LH Power Spectrum Five waveguide modules, every starting an alternate N || range, are utilized to drive the required off-pivot seed current profile. These are situated around 90 o (~2m.) beneath the detachable midplane. Expanded material science display observed an ingestion to be irrelevant for off-pivot drive at r > 0.8. Recurrence can be brought down for high N || dispatch at external plasma locale, in this manner easingdesign of waveguide launcher. The custom-made LH range has taking after parameters: f (GHz) N || P (MW) I disc/I sd 3.6 1.5 2.41 0.15 3.6 1.8 4.92 0.28 3.6 2.5 6.29 0.25 3.6 3.5 8.36 0.20 2.5 5.0 9.02 0.12 ARIES-AT Total - <j f > (A/cm 2 ) 2.5 3.5 1.8 5.0 N || = 1.5 r

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Enhanced Core Radiation Impacts Current Drive Power Requirement High f rad operation with debasement infusion as well as radiative mantle was analyzed for ARIES-RS so as to diminish divertor warm load. Higher Z eff has two noteworthy consequences for current drive: - Increased collisionality brings about altered boostrap current profile; - Lower current drive productivity In ARIES-RS, higher Z eff decreases standardized current drive effectiveness, and prompts to higher off-pivot current drive control. g B = <n>I p R/P CD

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ARIES-ST Uses Neutral Beams to Drive Off-Axis Seed Current NBI was utilized on the grounds that: (1) absence of entrance with LHW and HHFW, and (2) need of toroidal revolution drive for wrinkle adjustment. 5% I p driven by 32 MW @ 120 keV, R tang = 4.0 m. Produced turn: <V f > ~ 80 km/s ~ 4% V a Rigid-body supposition. NBCD investigation done by NFREYA with vast r/R redress. Little on-pivot seed ebb and flow driven by potato-circle particles - a subject of on-going exploration.

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ALL RF Launchers Fit in One Blanket Sector To minimize interruption in power center requires RF launchers with high power thickness (MW/m 2 ) capacities. - ICRF/FW : Folded waveguide [ ORNL ] - LHW : Active/latent waveguide grille [ ITER-EDA ] All launcher modules fit in one extraordinary cover division with insignificant effect on cover execution. In ARIES-RS: Total first-divider infiltration = 2.53 m 2 = 0.6% of divider territory.

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Single Folded Waveguide Launcher and Coax Feed Capacitive stomach lessens spiral thickness of waveguide, and gives additional protecting; voltage can be brought down by legitimate molding.

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Front View of LH Launcher Modules for ARIES-RS Each base unit comprises of a dynamic/uninvolved waveguide combine displayed after ITER-EDA.

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Issues and Areas for Future Research Heating and Current Drive: - LHW infiltration is restricted in high-b plasma; HHFW is a probability, however needs imaginative radio wire idea; - Investigate the progression of RF ebb and flow profile control - demonstrating, and physical science and innovative contraints - Refine displaying ability to self-reliably decide MHD stable harmony with bootstrap and remotely determined streams; - Use wave range figured for RF launcher in beam following examination; - Study parts of RF in turn era and transport boundary control RF Launcher: - EM field examination inside collapsed waveguide in reasonable geometry, and analyzes in a tokamak domain - Detailed launcher cooling and warm stretch investigation - Structural material decision in SiC environment : SiC with metal covering - Wave coupling and stacking amid plasma drifters

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Interactions with Community and Publications The CURRAY code was produced mutually with General Atomics, and is utilized for ARIES concentrate, quick wave investigates DIII-D, and NSTX HHFW considers. The utilization of FWCD in ARIES mostly propelled FWCD investigates DIII-D in the mid-90's. Connections with GA RF physicists prompted to the augmentation of RF and NBI j/p scalings to low angle proportion administration for circular tori. Cooperations with ORNL RF Group were helpful in the outline of collapsed waveguide launchers on ARIES-RS. UCSD will co-have fourteenth RF Topical Conference in 2001. Number of composed and co-created papers on related points: 6 in companion investigated diaries, an