| Line 1 was replaced by lines 1-77 |
| - HEOX is a |
| + !Oxford Intruments 3He Sorption Cryostat |
| + |
| + HEOX is a 3He cryostat with a sorption 3He pump. All gas handling is |
| + inside the cryostat, there are therefore no tubes to a pump outside. |
| + |
| + After putting into operation, some questions are still open: |
| + |
| + * The sample space has a diameter of about 40 mm. Around this tube, |
| + there is 4.5 mm liquid helium. This produces background, |
| + especially on inelastic measurements. A [test on TASP|HeoxOnTasp] shows |
| + background count rates of the order of 40 counts/min. which seems |
| + to be inacceptable. |
| + |
| + * In principle, it should be possible to combine the 3He insert with |
| + the MA09 cryomagnet. It is not yet clear, if it really works, and |
| + there will also be the problem with the LHe background. |
| + |
| + * For powders, it is not clear if the thermal contact inside the |
| + sample container is good enough to ensure the expected sample |
| + temperature. |
| + |
| + ''Some test results'' |
| + |
| + Hold times: |
| + |
| + |minimum T|0.33 K|22h |
| + | |0.5 K|25h |
| + | |0.7 K|32h |
| + |
| + LS340 Settings: |
| + |
| + * Sensor A : 1K-pot |
| + * Sensor B : Sorb. (thats the cryo pump for the 3He) |
| + * Sensor C : 3He-pot Cernox for 1.2K<T<320K |
| + * Sensor D : 3He-pot Speer for T<10K |
| + * Sorb heater: 34 Ohm |
| + * 3He-pot heater: 200 Ohm |
| + |
| + [Inelastic background on TASP|HeoxOnTasp] |
| + |
| + !Operation with two heaters: |
| + |
| + Heox starts up with the second PID loop (Analog Out2) enabled |
| + and loop 1 to control the temperature of the Sorb (Ch B) |
| + |
| + The switch on the heater cable allows to operate the Sorb on loop 1 (the main loop) and simultaneously |
| + heat the 3He-pot with loop 2 and visa versa. |
| + |
| + For low Temperature experiments <10K it is recommended to use: Sorb = loop1, 3He = loop2 while for higher |
| + temperatures Sorb = loop2, 3He = loop1 should be used. ''note:'' for the high temperatur setting the Cernox (channel C) |
| + should be used as the primary thermometer |
| + |
| + You can operate the system by regulating the Sorb and the 3He-pot temperature independently (controlmode 0) |
| + or by using both heaters cooperatively to control the 3He-pot temperature (controlmode 1) in this case the setpoints |
| + for both loops should have the same value. |
| + |
| + __INPORTANT:__ both heaters are disabled if any setpoint is exactly zero. In order to control the Temperature using only |
| + 1 heater the other set value should be small (not reachable) |
| + |
| + |
| + __sea_commands__ |
| + |
| + ''tt controlmode <n>'' ...sets control channel of loop 1 to B (n=0) or D (n=01) |
| + |
| + ''tt set2 <n.n>'' ... setpoint of loop 2 in K |
| + |
| + ''tt send pid n:P,I,D'' ... set PID values of loop n (1 or 2) |
| + |
| + ''tt send cset n:<channel>,<unit>,<off/on>,<power enable>'' ...sets the channel (A,B,C,D) |
| + which will be used by loop <n> |
| + (e.g. tt send cset 2:D,1,1 sets loop 2 to control the 3He-pot heater |
| + |
| + ''tt send pid?n'' query PID settings of loop n |
| + |
| + ''tt send cset?n'' query control settings of loop n |
| + |
| + [helium3a.jpg] |
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