Deuterium Retention in and Release from Beryllium ... Deuterium Retention in and Release from...

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  • D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011

    U C S D University of California San Diego

    Deuterium Retention in and Release from Beryllium Resulting

    from High Flux Plasma Exposure

    aMax-Planck-Institut für Plasmaphysik, 85748 Garching, Germany bGeneral Atomics, San Diego, CA 92121, USA

    cUniversity of California San Diego, CA 92093, USA

    T. Schwarz-Selingera, M. Oberkoflera, H. Xub

    R. Doernerc and the PISCES Teamc

    Max-Planck-Institut für Plasmaphysik

    13th International Workshop on Plasma-Facing Materials and Components for Fusion Applications /

    1st International Conference on Fusion Energy Materials Science

  • D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011

    U C S D University of California San Diego

    Motivation: T Removal in ITER

    T Retention in pure Beryllium

     implantation: saturation at low levels

     codeposition: unlimited

    main wall erosion dominated, but:

    - gaps are potential deposition zones!

    - resessed wall elements

     assessing T removal by baking at

    240°C / 350°C

  • D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011

    U C S D University of California San Diego

    K. Sugiyama et al., PSI-19 (doi:10.1016/j.jnucmat.2010.09.043):

     ITER baking temperatures 240ºC (main wall) 350ºC (divertor)

    assessment of T removal in ITER by wall baking

    Here:  thick codeposits  is removal efficiency increased for longer hold times?

    (is release determined by diffusion or by trap/bond energies)

    0 2000 4000 1E-3

    0.01

    0.1

    1

    100

    200

    300

    400

    500

    600

    D fl

    ux (1

    01 5 D

    c m

    -2 s-

    1 )

    time (sec)

    0. 3

    K/ se

    c

    ram p tem

    perature (°C )

    600 eV D3 + implanted in 300 nm thick

    TVA deposited Be layers

    350°C

  • D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011

    U C S D University of California San Diego

    outline

    Deuterium Retention in and Release from Beryllium Resulting

    from High Flux Plasma Exposure

    D release from thick codeposits for long hold times at 240°C / 350°C

     single / multilayer co-deposits

     high flux codeposit

     implanted Be

     model system: magnetron sputtered D/Be

    Comparing D release from

  • D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011

    U C S D University of California San Diego

    PISCES-B

    W witness plate

    B fieldBe target

    optional Be

    seeding

    target: bias: < -170V results in E < 150eV + high flux: D ion flux: < 5·1018 cm-2s-1 Be seeding: nBe/nD < 3% - one sample at a time - implantation profile

    witness plate: energy of sputtered Be: few eV energy of reflected Be: < 10 eV energy of reflected D: < 15-40 eV - low fluxes: Be flux:

  • D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011

    U C S D University of California San Diego

    H.W. Xu et al., Fusion Sci. Technol. 51, 547-552 (2007)

    model system: magnetron sputtered Be

    3 x 100Watt, 6 mTorr, 80% Ar, 20% D2

    energy of sputtered Be: few eV energy of reflected Ar: few eV energy of ionized Ar:

  • D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011

    U C S D University of California San Diego

    D release from multilayer codeposits

  • D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011

    U C S D University of California San Diego

    D release from multilayer codeposits

    Present predictions for T release in ITER are based on pure Be targets /

    codeposits.

    Actual ITER codeposits will be multilayers with BeO interfaces in between.

    Be/D

    Be/D

    BeO

    Question: Do BeO layers influence the D

    release?

    here: - collecting PISCES-B on W witness

    - interrupted exposure for several hours / bring to air to allow an oxide layer

    to grow

    Diffusion barrier? Shift in release temperature?

  • D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011

    U C S D University of California San Diego

    experiment: low flux codeposit

    - single layer: Be target + cap, bias = -100V  ED = 22 eV  = 1.2 · 1014 Be/cm-2s-1, t = 10000 sec

    D release from single layer codeposit

    W

  • D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011

    U C S D University of California San Diego

    100 200 300 400 500 600

    1E-3

    0.01

    0.1

    1

    D fl

    ux (1

    01 6 D

    /s )

    sample temperature (°C)

    PISCES-B, 300 K single layer

    0.3 K/sec

    2.41017D/cm2

    tm s2

    2C W

    B

    experiment: low flux codeposit

    - single layer: Be target + cap, bias = -100V  ED = 22 eV  = 1.2 · 1014 Be/cm-2s-1, t = 10000 sec

    D release from single layer codeposit

    TDS:

    d = 100 nm D/Be = 0.2

    W

  • D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011

    U C S D University of California San Diego

    100 200 300 400 500 600

    1E-3

    0.01

    0.1

    1

    8.91017D/cm2

    4.81017D/cm2

    D fl

    ux (1

    01 6 D

    /s )

    sample temperature (°C)

    PISCES-B, 300 K first layer second layer

    0.3 K/sec

    4.21017D/cm2

    tm s2

    1C W

    B / t

    m s2

    2C W

    B

    experiment

    - 2 identical runs: Be target + cap, bias = -100V  ED = 22 eV  = 1.2 · 1014 Be/cm-2s-1, t = 10000 sec

    - replacing one half piece of circular W witness plate after first run

    D release from multilayer codeposit

    TDS:

    d = 2 x 100 nm D/Be = 0.2

    BeO expected 5-10 nm

    W

  • D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011

    U C S D University of California San Diego

    100 200 300 400 500 600

    1E-3

    0.01

    0.1

    1

    8.91017D/cm2

    4.81017D/cm2

    D fl

    ux (1

    01 6 D

    /s )

    sample temperature (°C)

    PISCES-B, 300 K first layer second layer double layer

    0.3 K/sec

    4.21017D/cm2

    tm s2

    1C W

    A / t

    m s2

    1C W

    B / t

    m s2

    2C W

    B

    experiment

    - 2 identical runs: Be target + cap, bias = -100V  ED = 22 eV  = 1.2 · 1014 Be/cm-2s-1, t = 10000 sec

    - replacing one half piece of circular W witness plate after first run

    D release from multilayer codeposit

    TDS:

    d = 2 x 100 nm D/Be = 0.2

    BeO expected 5-10 nm

    W

  • D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011

    U C S D University of California San Diego

    conclusion:

     oxide interfaces (several nm thick) do not influence D release

    D release from multilayer codeposit

    100 200 300 400 500 600

    1E-3

    0.01

    0.1

    1

    8.91017D/cm2

    4.81017D/cm2

    D fl

    ux (1

    01 6 D

    /s )

    sample temperature (°C)

    PISCES-B, 300 K first layer second layer double layer sum first+second

    0.3 K/sec

    4.21017D/cm2

    tm s2

    1C W

    A / t

    m s2

    1C W

    B / t

    m s2

    2C W

    B

    d = 2 x 100 nm D/Be = 0.2

    BeO expected 5-10 nm

    W

  • D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011

    U C S D University of California San Diego

    comparing different codeposits

  • D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011

    U C S D University of California San Diego

    PISCES-B low flux (witness plate) codeposit

    collecting Be and D (on W) sputtered/reflected from a Be target:

    thermal desorption:

    100 200 300 400 500 600

    1E-4

    1E-3

    0.01

    0.1

    1

    D fl

    ux (1

    01 6 D

    c m

    -2 s-

    1 )

    sample temperature (°C)

    sum as D2 as HD

    tm s2

    1C W

    B

    structurally modified, supersaturated (D2 bubbles / a-Be-D)

    Be-D2 BeO defects by coll. cascade

  • D retention in and release from Be.ppt, © Thomas Schwarz-Selinger, PFMC13 I-19, 12. May 2011

    U C S D University of California San Diego

    100 200 300 400 500 600

    0.01

    0.1

    1

    nD = 4.2 10 17 D/cm2

    low flux codeposit: D = 2.4  10

    15 D/(cm2s)

    Be = 1.2  10 14 Be/(cm2s)

    EBe< eV, ED= 21 eV T = 320 K t = 10000 sec D/Be = 0.34, d= 100 nm

    re m

    ai ni

    ng D

    (D T/D

    0)