E.4 Expressing the coefficient before ∂F0∕∂𝜀 in terms of δE and δB

[Note that

∂δA⊥-= − (δE ⊥ + ∇⊥δΦ ),
 ∂t
(301)

where ∂δA∕∂t is of O(λ2). This means that δE + δϕ is of O(λ2) although both δE and δϕ are of O(λ).]

Note that

∂⟨v ⋅δA⟩α     ∂⟨δA∥⟩α      ∂ ⟨δA ⟩α
--------- = v∥-------+ v ⊥ ⋅------
    ∂t        ∂⟨∂δtA ⟩          ∂t
          = v∥----∥-α+ ⟨v⊥ ⋅(− δE − ∇δΦ )⟩α
                ∂t
          ≈ v∥∂⟨δA∥⟩α− ⟨v⊥ ⋅δE⟩α                        (302)
                ∂t
where use has been made of v⋅∇δϕ⟩≈ 0, This indicates that vδEα is of O(λ1)δE. Using Eq. (302), the coefficient before ∂F0∕∂𝜀 in Eq. (138) can be further written as
  q [ ∂ ⟨v ⋅δA⟩α   (            q e∥             )         ]
− m- −----∂t--- −  v∥e∥ + VD − m-Ω-× ∇X ⟨v ⋅δA ⟩α ⋅∇X ⟨δΦ⟩α
      [                        (                             ) ⟨           ⟩  ]
= − q- − v∥∂⟨δA-∥⟩α + ⟨v⊥ ⋅δE ⟩α − v∥e∥ + VD − q-e∥× ∇X ⟨v ⋅δA ⟩α ⋅ − δE − ∂δA
    m [      ∂t                             m Ω                         ∂t⟨  α  ⟩ ]
    q-    ∂⟨δA-∥⟩α              (            q-e∥             )              ∂A∥-
≈ − m  − v∥  ∂t   + ⟨v⊥ ⋅δE ⟩α − v∥e∥ + VD − m Ω × ∇X ⟨v ⋅δA ⟩α ⋅⟨− δE⟩α + v∥  ∂t
    q [           (            q e∥             )      ]                         α
= − m- ⟨v ⊥ ⋅δE ⟩α + v∥e∥ + VD − m Ω-× ∇X ⟨v⋅δA ⟩α ⋅⟨δE⟩α
    q [           (              ⟨δB  ⟩)       ]
≈ − -- ⟨v⊥ ⋅δE ⟩α + v∥e∥ + VD + v∥---⊥-- ⋅⟨δE⟩α .                               (303)
    m                             B0
Using Eq. (303) and (), gyrokinetic equation (138) is finally written as
[ ∂  (            ⟨δE ⟩α × e∥    ⟨δB⊥ ⟩α )     ]
 ∂t +  v∥e∥ + VD +----B-----+ v∥--B----  ⋅∇X  δf
    (                  0  )         0
= −  ⟨δE⟩α-×-e∥+ v∥⟨δB⊥-⟩α- ⋅∇XF0
    [    B0     (    B0              )       ]
  q-                           ⟨δB-⊥⟩α-        ∂F0-
− m  ⟨v⊥ ⋅δE ⟩α + v∥e∥ + VD + v∥  B0    ⋅⟨δE⟩α  ∂𝜀 .         (304)