Investigation of peeling-ballooning stability prior to transient outbursts accompanying transitions out of H-mode in DIII-D
[1];
[2];
[2];
- Univ. of California San Diego, La Jolla, CA (United States); Princeton Univ., Princeton, NJ (United States)
- General Atomics, San Diego, CA (United States)
- Univ. of California San Diego, La Jolla, CA (United States)
- Princeton Univ., Princeton, NJ (United States)
- Univ. of California, Los Angeles, CA (United States)
- Univ. of York, York (United Kingdom)
Here, the H-mode transport barrier allows confinement of roughly twice as much energy as in an L-mode plasma. Termination of H-mode necessarily requires release of this energy, and the timescale of that release is of critical importance for the lifetimes of plasma facing components in next step tokamaks such as ITER. H-L transition sequences in modern tokamaks often begin with a transient outburst which appears to be superficially similar to and has sometimes been referred to as a type-I edge localized mode (ELM). Type-I ELMs have been shown to be consistent with ideal peeling ballooning instability and are characterized by significant (up to ~50%) reduction of pedestal height on short (~1 ms) timescales. Knowing whether or not this type of instability is present during H-L back transitions will be important for planning for plasma ramp-down in ITER. This paper presents tests of pre-transition experimental data against ideal peeling-ballooning stability calculations with the ELITE code and supports 2 those results with secondary experiments that together show that the transient associated with the H-L transition is not triggered by the same physics as are type-I ELMs.
- Research Organization:
- General Atomics, San Diego, CA (United States)
- Sponsoring Organization:
- USDOE Office of Nuclear Energy (NE)
- Grant/Contract Number:
- FC02-04ER54698; AC02-09CH11466; FG02-07ER54917; FG02-08ER54984
- OSTI ID:
- 1356320
- Alternate ID(s):
- OSTI ID: 1228230
- Journal Information:
- Physics of Plasmas, Vol. 22, Issue 5; ISSN 1070-664X
- Publisher:
- American Institute of Physics (AIP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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