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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:6
UID:UW-Physics-Event-8706
DTSTART:20240401T170000Z
DTEND:20240401T181500Z
DTSTAMP:20260413T223556Z
LAST-MODIFIED:20240401T094624Z
LOCATION:1227 Engineering Hall
SUMMARY:“Disruption physics gaps encountered in the SPARC design per
 tinent to the design of the ARC power plant”\, Plasma Physics (Physi
 cs/ECE/NE 922) Seminar\, Ryan Sweeney\, MIT PSFC/CFS
DESCRIPTION:R. Sweeney on behalf of the SPARC and ARC Teams 
\n<br>
\n
 Addressing climate change with a tokamak-based fusion power plant requ
 ires that plasma disruptions pose a low risk to day-to-day operation o
 r to early end of life for in-vessel components.  Advancing disruption
  resilience requires a tokamak that can create a reactor-scale environ
 ment for testing proposed solutions but can also survive disruptions i
 f the solution fails\, enabling a fast-learning cycle. Commonwealth Fu
 sion Systems (CFS) is developing disruption resilient tokamaks equippe
 d with robust plasma control software to meet this need. SPARC is a co
 mpact (R=1.85 m)\, high field (12.2 T) and current (8.7 MA) tokamak un
 der construction in Devens\, MA\, designed to start operations in 2026
 .  Its first mission is to demonstrate Q > 1 and will then be used to 
 answer questions critical to the design of the ARC fusion power plant.
  SPARC is conservatively designed to structurally survive a battery of
  worst case disruption events and to tolerate melt events with tungste
 n based first wall components and no active cooling\, and is equipped 
 with state-of-the-art mitigation systems and diagnostics to retire the
  disruption risks for ARC. This talk will start with a brief overview 
 of the status of the SPARC project with a focus on disruption systems.
  The remainder of the talk will address the disruption physics that se
 t the most challenging requirements and drove actuator decisions for S
 PARC\, highlighting where the larger community can complement the phys
 ics basis for the ARC power plant now under design. Disruptions are a 
 known challenge\, and the SPARC and ARC Teams welcome support as we sp
 rint toward the solution in an effort to deploy fusion on the timescal
 e that climate change requires.  
\n<br>
\n<br>
\n<b>Supplementary tex
 t on open disruption physics questions\, with suggestions for studies:
 </b> 
\nThe predicted plasma current quench durations\, based on ITPA 
 scalings\, drive the structural design of the SPARC vacuum vessel and 
 in-vessel components. Improved physics understanding of these timescal
 es would better inform the ARC design. A massive gas injection (MGI) s
 ystem with six toroidally and poloidally distributed valves is the fir
 st mitigation technology that will be deployed on SPARC. Empirical and
  simulation comparisons of MGI with shattered pellet injection (SPI) a
 nd other alternatives would better inform the actuator decision for AR
 C. A novel runaway electron mitigation coil (REMC) is designed for SPA
 RC and predictions suggest it will fully prevent runaway formation dur
 ing disruptions at high current. Exploration of other runaway preventi
 on solutions could provide optionality for the ARC design. Parallel he
 at fluxes from unmitigated and even some mitigated thermal quenches po
 se a risk to melting plasma facing tiles and other in-vessel component
 s in SPARC. CFS and IPP Garching are exploring this physics on AUG\; e
 xploration on other machines would complement this planned dataset. Th
 e magnetic energy outside of the vacuum vessel can significantly incre
 ase the severity of disruption heat fluxes. Further understanding of t
 his conversion would help to design ARC for these loads. While ARC wil
 l be designed to operate a single plasma scenario\, SPARC is tasked wi
 th identifying the optimal ARC scenario and thereby must explore param
 eter space. Demonstrating physics-based disruption observers and avoid
 ance could support SPARC operation\, as well as physics studies of dis
 ruption causes including fusion-relevant material failure modes. 
URL:https://www.physics.wisc.edu/events/?id=8706
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