??(?)? D4

1
?????????????????????????

• ??(?)? D4
• ????

2
?????????????????????????
????????? PSD (photon-stimulated
desorption) ?????????? (ion-induced
desorption) ???????????? (micrometeoroid
impacts) ??? (thermal desorption)
Na?K????????????????? ????????Na?K????????? ????
?????????? ??????Na,K????????????????
????????????????D2?????2????? Potter and Morgan,
1998
3
?????????????etc
SiO2????????????? Na?K????????
??????????????????????????????
?????
????
Na
Na
K
??????
O
O
O
Si
Si
Si
O
O
O
O
O
4
Na???????????
????????? Nexp(-mgh/kT)
Smyth and Marconi, 1995 ?????????????????
Potter and Morgan, 1998 ?????cosn???????????
5
?????????????
?????????????Ca?Fe?Si?Al?Mg???????????????????????
???????????(Flynn and Stern1996)(Stern et
al.1997) Na?K????PSD?????????????????????????
????????? ???????????Na??????????????????????????
(????Yakshinsky and Maday1999?????????????PSD?
?????Na????????????????????????PSD???Na?K?????????
??)
6
????????PSD???2???????????????????
Potter et al.,2000
????
????
???????????
????????????
?Lunar Phase Angle(LPA)???
LPA??30???????
?????????????????surface density?????????? ???????
?????
??????????????surface density???????????
7
?????Na????
???????NaD2????2?????????????? ?????????????1993?2
000???????? Wilson et al. 2006
8
????????????
9
??????????????
?????????????????E/q(?????/??)????? ???????????m/
q(??/??)??????
10
IMA-MA TOF Mass analysis
positive ion
Carbon foil
????????????????????? ???????????????????????????
??????????????????????????????????????????
(Stop) Secondary electron
Electric Field
neutral
Negative ion
(Start) Secondary electron
Detector
11
????????????????(???)
Yokota et al. 2009 ?????????(IEA)????????????????
????(IMA)??????????????????????????????
12
????????????????
Yokota et al. 2009 IEA?????????????IMA???????????
?????????????????????
13
???????(1????)
Reflected solar wind H and He
Energy (keV)
The Moon-originating ions
Time of Flight (nsec)
14
TOF profile of Moon-originating ion
Least chi-square fitting
15
Fitting???????Ion flux
16
??????(7/0112/01)
17
??????(7/0112/30)
K
18
Na,K ion?????????????????

• Na?K????????????????????????????????????
• yokota et al. 2005????????????????????????????????
  ???(PSD?Sputtering???????????????)?????????????
• ???????????????????
• ???????????????Solar Zenith Angle??????SZA?????

19
???????????1
?????surface???PSD(Smith and Marconi
1995)(Mendillo et al. 1991)???????????????Na/Na?K
/K?????? ????????Sputtering???ion?flux(Elphic et
al 1991) ?????????????????????????????????? (Yoko
ta et al. 2005)?
20
???????????2
??????????????NaK????????????
????????
????????????
?????????????
Yokota,2005
21
?????????????????
Exospheric ions Surface-originated ions
Esw-VswBsw
BswIMF
Solar Wind (Vsw) UV
Solar zenith angle????? ???????????Pick up
ion? Flux??????
22
???????????
?????????SW??????Self pick up acceleration
??????? ???????????????????????????????????? ?????
??
Solar zenith angle????????????????Pick up
ion? vxB??????????????
23
SZA dependence of the Na ion flux
?????35/cm3 Apparent Scale Height?510km PSD flux
3.5x103 Sputtering flux 2.4x103
Simulation?yokota et al. 2005?????????
24
SZA dependence of the K ion flux
?????10/cm3 Apparent Scale Height?85km PSD flux
1.2x103 Sputtering flux 9.5x102
25
SZA?????????

• Na,K????flux???????????
• ??????????????????????????????????????????????????
  ???????????
• SZA????????SZA????SZA?????????????????????(??K???
  )
• K????????????????????????
• ???sub-solar point????SZA?????????????????????????
  ???????

26
?????????????
Suprathermal desorption (PSD??????????)
Thermal desorption
?????????? SZA?????????
27
????????????????
Suprathermal desorption
Thermal desorption
Sub-solar point????SZA? ???????????????? ???????
28
???

• ?????TOF???????????????????????Na???K???????????
  ??????(K?????????????)
• Na,K????????????????SZA???yokota et al.
  2005???????????????????????????????????????????SZA
  ???????????????????????????????????????
• ???????????????????????

29
Future Works

• ???SZA??????????????????????????
• Na,K?????????????????????
• ??????????????????????????????????

30
Orbit 20081001-1010
31
Experimental TOF profile compared with computed
one.
O ions TOF profile TOF profile is changed with
incident ion energy
count
TOF(nsec)
32
Comparison of the two data sets in flux
33
Potter Morgan 1998
False color images of sodium d2 emission from
lunar exosphere observed by Evans coronagraph
Potter and Morgan, 1998
34
??????????????????????Na
Picked-up ion(Na)??? pointA???100km???30
YokotaSaito,2004

• Elphic et al.1991?????????????????????????????
  (100km??)??????????????????
• Yokota and Saito 2004