Russ Doerner - Controlled Fusion Atomic Data Center

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Be layer forms on C targets with a complicated three dimensional structure ~0.1 % Be seeding ∆m = - 5 mg AES - 85 % Be, 10% O & 5% C ATJ graphite Not exposed No Be seeding ∆m = - 62 mg Plasma conditions: Γ D ~3x10 18 cm -2 s -1 , T e ~ 6eV, n e ~ 10 12 cm -3 , T ~500 K, D Ion Fluence ~2x10 22 cm -2 UCSD University of California San Diego R. <strong>Doerner</strong>, March 22, 2005 PSIF workshop, ORNL
Do we understand why these Be layers form? In equilibrium: Deposition Rate of Be = Removal Rate of Be Be Deposition Rate = f Be Γ pl (1 – R f ) ~0 for Be on C where, f Be = plasma Be concentration, Γ pl = plasma flux, R f = reflection coefficient Be Removal Rate = c Be Y Be Γ pl (1-R d ) where, c Be = Be surface concentration, Y Be = sputtering yield of Be due to 50 eV deuterium ions (=0.02), R d = redeposition fraction (~20% from WBC simulation) So the equilibrium surface concentration of Be, c Be , should be: c Be = f Be / Y Be (1-R d ) = 0.001 / 0.02(1-0.2) = ~ 6% Beryllium-carbide formation may be responsible for erosion suppression. If Be 2 C surface layer, then Y = 0.002 (from TRIMSP) and c Be = f Be / Y Be2C (1-R d ) = 0.001 / 0.002(1-0.2) = ~ 60% UCSD University of California San Diego R. <strong>Doerner</strong>, March 22, 2005 PSIF workshop, ORNL
Page 1 and 2: Erosion Behavior of Carbon and Tung
Page 3 and 4: PISCES-B, and Its Associated Surfac
Page 5 and 6: PISCES-B linear plasma device simul
Page 7 and 8: PISCES-B operation above 6 eV T e p
Page 9 and 10: A small beryllium impurity concentr
Page 11: Be layer formation effectively elim
Page 15 and 16: WPM samples show collection of bery
Page 17 and 18: Be impurities from the ITER first w
Page 19 and 20: What will be the result of Be layer
Page 21 and 22: The dynamic behavior of the Be laye
Page 23: Be impurities may dominate PMI (spe

Russ Doerner - Controlled Fusion Atomic Data Center

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