UB=12B2oμo
UB=12μo{μoqv4πr2.r3ea3e.sin2(ϕ).Z}2
UB=μo2{qv4πr2.r3ea3e}2sin4(ϕ).Z2
where Z has two terms,
Z={∫sec(θ0)1e−x.yae{√y2−1}dy+∫cos(θ0)1e−xaey{1y4}dy}
As x≤2re and θ0 is small, y=sec(θ0)≈1, √y2−1≈0 because 0≤y≤sec(θ0).
We simplify by letting the first term of Z be zero.
∫sec(θ0)1e−x.yae{√y2−1}dy=0
Z=∫cos(θ0)1e−xaey{1y4}dy
Then we consider, the average of UB over one period, ie its power,
¯UB=1T∫T0UBdt=1T∫T0μo2{qv4πr2.r3ea3e}2sin4(ϕ)(∫cos(θ0)0e−xaey{1y4}dy)2dt
¯UB=μo2T{qv4πr2.r3ea3e}2∫T0sin4(ϕ)(∫cos(θ0)0e−xaey{1y4}dy)2dt
but
x2=r2e+r2e−2r2ecos(ϕ)=2r2e(1−cos(ϕ))
x=re√2(1−cos(ϕ))=2resin(ϕ/2)
¯UB=μo2T{qv4πr2.r3ea3e}2∫T0sin4(ϕ)(∫cos(θ0)0e−2resin(ϕ/2)aey{1y4}dy)2dt
dϕdt=ω is a constant.
¯UB=μo2Tω{qv4πr2.r3ea3e}2∫2π0sin4(ϕ)(∫cos(θ0)0e−2resin(ϕ/2)aey{1y4}dy)2dϕ
where y=cos(θ),
¯UB=μo2Tω{qv4πr2.r3ea3e}2∫2π0sin4(ϕ)(∫θ00−e−2resin(ϕ/2)aecos(θ){sin(θ)cos4(θ)}dθ)2dϕ
Consider,
h=e−2resin(ϕ/2)aecos(θ)
h′θ=e−2resin(ϕ/2)aecos(θ)(+2resin(ϕ/2)aecos2(θ)).(−sin(θ))
h′θ=−h.(2resin(ϕ/2)sin(θ)aecos2(θ))
h′θ=e−2resin(ϕ/2)aecos(θ)(+2resin(ϕ/2)aecos2(θ)).(−sin(θ))
h′θ=−h.(2resin(ϕ/2)sin(θ)aecos2(θ))
¯UB=μo2Tω{qv4πr2.r3ea3e}2a2er2e∫2π0sin2(ϕ)(∫θ00−e−2resin(ϕ/2)aecos(θ)reae2sin(ϕ/2)sin(θ)cos2(θ){cos(ϕ/2)cos2(θ)}dθ)2dϕ
¯UB=μo2Tω{qv4πr2.r3ea3e}2a2er2erre∫2π0sin2(ϕ)(∫θ00h′{cos(ϕ/2)cos2(θ)}dθ)2dϕ
¯UB=μo2Tω{qv4πr2.r3ea3e}2a2er2e∫2π0(sin(ϕ)cos(ϕ/2)∫θ00h′θ{1cos2(θ)}dθ)2dϕ--- (1)
Integrating by parts,
then, let,
Π=(sin(ϕ)cos(ϕ/2)∫θ00h′{1cos2(θ)}dθ)2
Π=(hsin(ϕ)cos(ϕ/2)cos2(θ)+2aere∫θ00hreae2sin(ϕ/2)sin(θ)cos2(θ)cos(ϕ/2)cos(θ)dθ)2
Π=(hsin(ϕ)cos(ϕ/2)cos2(θ)+2aecos(ϕ/2)re∫θ00h′θ1cos(θ)dθ)2---(2)
∫θ00h′θ1cos(θ)dθ=h1cos(θ)+∫θ00hsin(θ)cos2(θ)dθ---(3)
and
∫θ00hsin(θ)cos2(θ)dθ=ae2resin(ϕ/2)∫θ00hreae2sin(ϕ/2)sin(θ)cos2(θ)dθ
=−ae2resin(ϕ/2)∫θ00h′θdθ
=−ae2resin(ϕ/2)∫θ00h′θdθ=−|ae2resin(ϕ/2)h|θ0---(4)
Substituting (4) into (3), (2) and (1), we have,
¯UB=μo2Tω{qv4πr2.r3ea3e}2a2er2e∫2π0(|1cos2(θ)e−2resin(ϕ/2)aecos(θ)2cos2(ϕ/2)sin(ϕ/2)|θ00+|2aerecos(θ)e−2resin(ϕ/2)aecos(θ)cos(ϕ/2)|θ00−|a2er2ecot(ϕ/2)e−2resin(ϕ/2)aecos(θ)|θ00)2dϕ
with the substitution, h=e−2resin(ϕ/2)aecos(θ)
Let III|2π0 be the integral,
III|2π0=∫2π0(|1cos2(θ)e−2resin(ϕ/2)aecos(θ)2cos2(ϕ/2)sin(ϕ/2)|θ00+|2aerecos(θ)e−2resin(ϕ/2)aecos(θ)cos(ϕ/2)|θ00−|a2er2ecot(ϕ/2)e−2resin(ϕ/2)aecos(θ)|θ00)2dϕ
and consider,
(a+b+c)2=a2+b2+c2+2ab+2ac+2bc
let,
a=|1cos2(θ)e−2resin(ϕ/2)aecos(θ)2cos2(ϕ/2)sin(ϕ/2)|θ00
b=|2aerecos(θ)e−2resin(ϕ/2)aecos(θ)cos(ϕ/2)|θ00
c=−|a2er2ecot(ϕ/2)e−2resin(ϕ/2)aecos(θ)|θ00
then consider,
h=e−2resin(ϕ/2)aecos(θ)
h′ϕ=e−2resin(ϕ/2)aecos(θ)(−2recos(ϕ/2)aecos(θ))12
h′ϕ=−h.recos(ϕ/2)aecos(θ)
This is a long tedious way home...
Note:
Π=(hsin(ϕ)cos(ϕ/2)cos2(θ)+2aere∫θ00hreae2sin(ϕ/2)sin(θ)cos2(θ)cos(ϕ/2)cos(θ)dθ)2
Π=(hsin(ϕ)cos(ϕ/2)cos2(θ)+2aecos(ϕ/2)re∫θ00h′θ1cos(θ)dθ)2---(2)
∫θ00h′θ1cos(θ)dθ=h1cos(θ)+∫θ00hsin(θ)cos2(θ)dθ---(3)
and
∫θ00hsin(θ)cos2(θ)dθ=ae2resin(ϕ/2)∫θ00hreae2sin(ϕ/2)sin(θ)cos2(θ)dθ
=−ae2resin(ϕ/2)∫θ00h′θdθ
=−ae2resin(ϕ/2)∫θ00h′θdθ=−|ae2resin(ϕ/2)h|θ0---(4)
Substituting (4) into (3), (2) and (1), we have,
¯UB=μo2Tω{qv4πr2.r3ea3e}2a2er2e∫2π0(|1cos2(θ)e−2resin(ϕ/2)aecos(θ)2cos2(ϕ/2)sin(ϕ/2)|θ00+|2aerecos(θ)e−2resin(ϕ/2)aecos(θ)cos(ϕ/2)|θ00−|a2er2ecot(ϕ/2)e−2resin(ϕ/2)aecos(θ)|θ00)2dϕ
with the substitution, h=e−2resin(ϕ/2)aecos(θ)
Let III|2π0 be the integral,
III|2π0=∫2π0(|1cos2(θ)e−2resin(ϕ/2)aecos(θ)2cos2(ϕ/2)sin(ϕ/2)|θ00+|2aerecos(θ)e−2resin(ϕ/2)aecos(θ)cos(ϕ/2)|θ00−|a2er2ecot(ϕ/2)e−2resin(ϕ/2)aecos(θ)|θ00)2dϕ
and consider,
(a+b+c)2=a2+b2+c2+2ab+2ac+2bc
let,
a=|1cos2(θ)e−2resin(ϕ/2)aecos(θ)2cos2(ϕ/2)sin(ϕ/2)|θ00
b=|2aerecos(θ)e−2resin(ϕ/2)aecos(θ)cos(ϕ/2)|θ00
c=−|a2er2ecot(ϕ/2)e−2resin(ϕ/2)aecos(θ)|θ00
then consider,
h=e−2resin(ϕ/2)aecos(θ)
h′ϕ=e−2resin(ϕ/2)aecos(θ)(−2recos(ϕ/2)aecos(θ))12
h′ϕ=−h.recos(ϕ/2)aecos(θ)
This is a long tedious way home...
Note: