A

molec s kg^{1}

Constant from Equation (1.a)

A
_{
surf
}

m^{2}

Surface area of the frozen sample

A
_{
S
}

m^{2} kg1

Specific surface area of the regolith available for adsorption

α

Pa^{1}

Langmuir adsorption constant (subscripts refer to the species)

B

m^{3} molec^{1}

Constant from Equation (1.b)

C

kg m molec^{1} s^{1}

Constant from Equation (1.c)

χ

dimensionless

Mass fraction (subscripts: Z = of dust; H2O = of water)

D
_{
eff
}

m^{2}s^{1}

Diffusivity (subscripts: eff = Effective Diffusivity; 0 = time independent) When bolded represents a 2 element vector with [H_{2}O HDO]

e
_{
sys
}

dimensionless

Pumping efficiency (pressure ratio between chamber and QMSinlet)

G

dimensionless

Rate coefficient matrix

γ
_{
Z
}

dimensionless

Volume fraction of dust in lag mantle

k

dimensionless

Rate constant, Superscripts: ads = adsorption, des = desorption, X = crossreaction substitution by vaporphase species. When bolded represents a 2 element vector with [H_{2}O HDO]

k
_{
B
}

m^{2} kg s^{2} K^{1}

Boltzmann Constant (1.38 × 10^{23})

J

molec m^{2} s^{1}

Molecular flux at a point in the apparatus

k

s^{1}

Langmuir adsorption kinetic constant, Subscripts: H2O, HDO, X = substitution; Superscripts: ads = adsorption, des = desorption

l

m

Thickness of an adsorbed monolayer of water (2.75 × 10^{10})

m
_{
H2O
}

kg molec^{1}

Mass of a single water molecule (2.99 × 10^{26})

M
_{
H2O
}

kg mol^{1}

Molar Mass (0.01802 for water)

N
_{
A
}

molec mol^{1}

Avogadro's Number (6.02 × 10^{23})

n

molec m^{3}

Number density of molecules

p

Pa

Pressure (subscripts: sat = Saturated Vapor Pressure)

R

m^{2}K^{1}s^{2}

Specific Gas Constant (462 for water)

R
_{
u
}

J mol^{1} K^{1}

Universal Gas Constant (8.3145)

ρ

kg m^{3}

Density (subscripts: Z = of dust; reg = of regolith; H2O = of water)

Ψ

J m^{3}

Thermodynamic Adsorption Constant

T

K

Temperature (subscripts: QMS = the tubing at the throat of the QMS)

t

s

Time (subscripts: 0 = initial time)

θ

dimensionless

Fraction of adsorption sites occupied by water molecules when bolded indicates a twoelement vector with [H_{2}O HDO]

V

m^{3} s^{1}

Pumping speed

z

m

Thickness of dust lag (subscripts: 0 = initial time)
