Quenching rate constants of metastable states of neon, argon, and krypton by mercury atoms

The steady-state electron swarm parameters in Hg/Ar mixtures are analysed using a Boltzmann equation in which the collision terms providing generation of secondary electrons via metastable Hg and Ar atoms presented in the preceding paper (see Y. Sakai et al., ibid., vol.22, p.276, 1989) are taken into consideration. The ratio of the Townsend first ionisation coefficient to the electric field strength, alpha /SiE, calculated using the present equation for E/N values from 5 to 1412 Td in Ar with various admixtures of Hg vapour (K=ratio of Hg to total gas atom concentrations from 2*10-4 to 2*10-2) is in good agreement with the experimental values of Burgmans and Smeets (1983). For E/N below 100 Td and K above 6*10-3 ionisation collision between two metastable Hg atoms is found to be the dominant process for electron multiplication. The influence of electron concentration on the swarm behaviour is discussed quantitatively.

Section: Collision Cross Sectionsmentioning

confidence: 79%

Boltzmann equation analyses of electron swarm parameters in Hg/Ar gas mixtures: effect of metastable Hg and Ar atoms

Sawada

Sakai

Tagashira

1989

“…This is understood because of the reduction of the Penning ionisation in the case of kryptonmercury. Using the experimental value of Wren and Setser (1981) for the total rate coefficient for depopulation of the 3P2 state of krypton, i.e. 4.08 X m3 s-l, which will be approximately equal to k i , ~~-~~, one obtains a value for k d , ~~ of about 1.2 X m3 S-'.…”

Section: Resultsmentioning

confidence: 99%

The ionisation coefficient in Kr-Hg mixtures

Burgmans¹,

Merks-Eppingbroek²

1984

The ionisation coefficient in Kr-Hg mixtures has been measured for E/n values between 2*10-20 V m2 and 2*10-18 V m2 and for a mercury atom fraction varying from 8*10-4 to 8*10-2. The experiments were performed with a parallel-plate apparatus in which the current is measured as a function of the plate separation at constant electric field. The ionisation coefficient was found to be a function of E/n and the mercury atom fraction only. The increase in the ionisation coefficient for small admixtures of mercury is mainly due to associative ionisation. From the experimental results the effective rate coefficient for excitation of the appropriate krypton states is obtained as a function of E/n, as well as the ratio of the rate coefficients for depopulation of these excited krypton states by nonionising collisions with krypton and ionising collisions with mercury atoms respectively.

“…Gundermann (see [1, p 174]) has pointed out that by adding a small amount of Ar into Ne, instabilities of the Ne discharge can be greatly suppressed due to the strong Penning effect between Ar atoms and metastable Ne atoms. According to [22], the quenching rate of metastable Ar atoms by Hg can be as high as 1×10 15 m −3 s −1 , which is considerable because the excitation rate of Ar in a fluorescent lamp is very low due to its high threshold energy. Therefore, we can infer that considerable quench of metastable Ar atoms by Hg atoms may break the condition, which may favour the occurrence of moving striation.…”

Section: Discussionmentioning

confidence: 99%

Model investigation on moving striations in low pressure Ar–Hg discharge: electron response to striation-like fields

Liu¹,

Zissis²,

Li³

et al. 2009

Simulation of the electron response to striation-like fields in fluorescent lamps is performed based on the numerical solution of the Boltzmann equation. Calculation results are presented and analysed. It is indicated that in a fluorescent lamp under the given condition, Ar is dominant in the energy loss by elastic collision and Hg is leading in the energy loss by inelastic collision. Furthermore, according to the analyses on relaxation length, the high energy part of the electron distribution function is non-local, which may cause ionization instabilities. By comparison with other works, it is here confirmed that metastable Ar atoms are crucial for the appearance of moving striations.